New articles on Astrophysics

[1] 2407.14578

Star-Disk Collisions: Implications for QPEs and Other Transients Near Supermassive Black Holes

We use Athena++ to study the hydrodynamics of repeated star-accretion disk collisions close to supermassive black holes, and discuss their implications for the origin of quasi-periodic eruptions (QPEs) and other repeating nuclear transients. We quantify the impact of the collisions on the stellar structure, the amount of stripped stellar debris, and the debris' orbital properties. We provide simple fitting functions for the stellar mass-loss per collision; the mass-loss is much larger after repeated collisions due to the dilute stellar atmosphere shock-heated in earlier collisions. The lifetime of the QPE-emitting phase set by stellar mass-loss in star-disk collision models for QPEs is thus at most ~100 years; it is shortest for eRO-QPE2, of order a few decades. The mass of the stripped stellar debris per collision and its orbital properties imply that currently observed QPEs are not powered by direct star-disk collisions but rather by collisions between the stellar debris liberated in previous collisions and the accretion disk (`circularization shocks'). We discuss how the hydrodynamics of this interaction can explain the diverse timing properties of QPEs including the regular timing of GSN 069 and eRO-QPE2 and the large flare-to-flare timing variations observed in eRO-QPE1. QPEs with recurrence times of many days, if observed, may have more regular timing.

[2] 2407.14579

Dark matter core creation depends on the timing of star formation

We study feedback-driven cold dark matter core creation in the EDGE suite of radiation-hydrodynamical dwarf galaxy simulations. Understanding this process is crucial when using observed dwarf galaxies to constrain the particle nature of dark matter. While previous studies have shown the stellar-mass to halo-mass ratio $(M_{\star} / M_{200})$ determines the extent of core creation, we find that in low-mass dwarfs there is a crucial additional effect, namely the timing of star formation relative to reionisation. Sustained post-reionisation star formation decreases central dark matter density through potential fluctuations; conversely, pre-reionisation star formation is too short-lived to have such an effect. In fact, large stellar masses accrued prior to reionisation are a strong indicator of early collapse, and therefore indicative of an increased central dark matter density. We parameterise this differentiated effect by considering $M_{\star,\mathrm{post}}/M_{\star,\mathrm{pre}}$, where the numerator and denominator represent the amount of star formation after and before $z\sim6.5$, respectively. Our study covers the halo mass range $10^9 < M_{200} < 10^{10} M_\odot$ (stellar masses between $10^4 < M_{\star} < 10^8 M_\odot$), spanning both ultra-faint and classical dwarfs. In this regime, $M_{\star,\mathrm{post}}/M_{\star,\mathrm{pre}}$ correlates almost perfectly with the central dark matter density at $z=0$, even when including simulations with a substantially different variant of feedback and cooling. We provide fitting formulae to describe the newfound dependence.

[3] 2407.14582

Effects of primordial fluctuations on relic neutrino simulations

After decoupling, relic neutrinos traverse the evolving gravitational imhomogeneities along their trajectories. Once they turn non-relativistic, this results in a significant amplification of the anisotropies in the cosmic neutrino background (C$\nu$B). Past studies have reconstructed the phase-space distribution of relic neutrinos from the local distribution of matter (accounting for the Milky Way halo and the surrounding large-scale structures), but have neglected the C$\nu$B anisotropies in the initial conditions of neutrino trajectories. Using our previously developed N-1-body simulation framework, we show that including these primordial fluctuations in the initial conditions can be important, as it produces similar effects on the abundance and anisotropies of the C$\nu$B as the inclusion of large-scale structures beyond the Milky Way halo. Interpretability of data from future C$\nu$B observatories like PTOLEMY therefore depends on correctly modelling these effects.

[4] 2407.14584

Echo Location: Distances to Galactic Supernovae From ASAS-SN Light Echoes and 3D Dust Maps

Light echoes occur when light from a luminous transient is scattered by dust back into our line of sight with a time delay due to the extra propagation distance. We introduce a novel approach to estimating the distance to a source by combining light echoes with recent three-dimensional dust maps. We identify light echoes from the historical supernovae Cassiopeia A and Tycho's SN in nearly a decade of imaging from the All-Sky Automated Survey for Supernovae (ASAS-SN). Using these light echoes, we find distances of $3.6\pm0.1$ kpc and $3.2^{+0.1}_{-0.2}$ kpc to Cas A and Tycho, respectively, which are generally consistent with previous estimates but are more precise. These distance uncertainties are primarily dominated by the low distance resolution of the 3D dust maps, which will likely improve in the future. The candidate single degenerate explosion donor stars B and G in Tycho are clearly foreground stars. Finally, the inferred reddening towards each SN agrees well with the intervening H I column density estimates from X-ray analyses of the remnants.

[5] 2407.14588

Forecasts and Statistical Insights for Line Intensity Mapping Cross-Correlations: A Case Study with 21cm x [CII]

Intensity mapping -- the large-scale mapping of selected spectral lines without resolving individual sources -- is quickly emerging as an efficient way to conduct large cosmological surveys. Multiple surveys covering a variety of lines (such as the hydrogen 21cm hyperfine line, CO rotational lines, and [CII] fine structure lines, among others) are either observing or will soon be online, promising a panchromatic view of our Universe over a broad redshift range. With multiple lines potentially covering the same volume, cross-correlations have become an attractive prospect, both for probing the underlying astrophysics and for mitigating observational systematics. For example, cross correlating 21cm and [CII] intensity maps during reionization could reveal the characteristic scale of ionized bubbles around the first galaxies, while simultaneously providing a convenient way to reduce independent foreground contaminants between the two surveys. However, many of the desirable properties of cross-correlations in principle emerge only under ideal conditions, such as infinite ensemble averages. In this paper, we construct an end-to-end pipeline for analyzing intensity mapping cross-correlations, enabling instrumental effects, foreground residuals, and analysis choices to be propagated through Monte Carlo simulations to a set of rigorous error properties, including error covariances, window functions, and full probability distributions for power spectrum estimates. We use this framework to critically examine the applicability of simplifying assumptions such as the independence and Gaussianity of power spectrum errors. As worked examples, we forecast the sensitivity of near-term and futuristic 21cm-[CII] cross-correlation measurements, providing recommendations for survey design.

[6] 2407.14593

Binarity at LOw Metallicity (BLOeM): I. a spectroscopic VLT monitoring survey of massive stars in the SMC

Surveys in the Milky Way and Large Magellanic Cloud revealed that the majority of massive stars will interact with companions during their lives. However, knowledge of the binary properties of massive stars at low metallicity, which approaches the conditions of the Early Universe, remains sparse. We present the Binarity at LOw Metallicity (BLOeM) campaign - an ESO large programme designed to obtain 25 epochs of spectroscopy for 929 massive stars in the SMC - the lowest metallicity conditions in which multiplicity is probed to date (Z = 0.2 Zsun). BLOeM will provide (i) the binary fraction, (ii) the orbital configurations of systems with periods P < 3 yr, (iii) dormant OB+BH binaries, and (iv) a legacy database of physical parameters of massive stars at low metallicity. The stars are observed with the LR02 setup of the giraffe instrument of the Very Large Telescope (3960-4570A, resolving power R=6200; typical signal-to-noise ratio S/N=70-100). This paper utilises the first 9 epochs obtained over a three-month time. We describe the survey and data reduction, perform a spectral classification of the stacked spectra, and construct a Hertzsprung-Russell diagram of the sample via spectral-type and photometric calibrations. The sample covers spectral types from O4 to F5, spanning the effective temperature and luminosity ranges 6.5<Teff/kK<45 and 3.7<log L/Lsun<6.1 and initial masses 8<Mini/Msun<80. It comprises 159 O-type stars, 324 early B-type (B0-3) dwarfs and giants (luminosity classes V-III), 309 early B-type supergiants (II-I), and 137 late-type supergiants. At least 75 stars are Oe/Be stars: 20 O-type and 55 B-type (13% and 10% of the respective samples). In addition, it includes four high-mass X-ray binaries, three stars resembling luminous blue variables, two bloated stripped-star candidates, two candidate magnetic stars, and 74 eclipsing binaries.

[7] 2407.14594

Unveiling the Milky Way dust extinction curve in 3D

Interstellar dust is a major foreground contaminant for many observations and a key component in the chemistry of the interstellar medium, yet its properties remain highly uncertain. Using low-resolution spectra, we accurately measure the extinction curve - a diagnostic of the grain properties - for 130 million stars, orders of magnitude more than previously available, allowing us to map its variation in the Milky Way and Magellanic Clouds in 3D in unprecedented detail. We find evidence that accretion is the dominant mechanism of grain growth in moderately dense regions, with coagulation dominating at higher densities. Moreover, we find that the extinction curve flattens in star-forming regions, possibly caused by cycling of large grains formed in molecular clouds, or by preferential destruction of small grains by supernova shocks.

[8] 2407.14595

Big Galaxies and Big Black Holes: The Massive Ends of the Local Stellar and Black Hole Mass Functions and the Implications for Nanohertz Gravitational Waves

We construct the $z=0$ galaxy stellar mass function (GSMF) by combining the GSMF at stellar masses $M_* \lesssim 10^{11.3} M_\odot$ from the census study of Leja et al. (2020) and the GSMF of massive galaxies at $M_* \gtrsim 10^{11.5} M_\odot$ from the volume-limited MASSIVE galaxy survey. To obtain a robust estimate of $M_*$ for local massive galaxies, we use MASSIVE galaxies with $M_*$ measured from detailed dynamical modeling or stellar population synthesis modeling (incorporating a bottom-heavy initial mass function) with high-quality spatially-resolved spectroscopy. These two independent sets of $M_*$ agree to within ${\sim}7$%. Our new $z=0$ GSMF has a higher amplitude at $M_* \gtrsim 10^{11.5} M_\odot$ than previous studies, alleviating prior concerns of a lack of mass growth in massive galaxies between $z\sim 1$ and 0. We derive a local black hole mass function (BHMF) from this GSMF and the scaling relation of SMBH and galaxy masses. The inferred abundance of local SMBHs above $\sim 10^{10}M_\odot$ is consistent with the number of currently known systems. The predicted amplitude of the nanohertz stochastic gravitational wave background is also consistent with the levels reported by Pulsar Timing Array teams. Our $z = 0$ GSMF therefore leads to concordant results in the high-mass regime of the local galaxy and SMBH populations and the gravitational wave amplitude from merging SMBHs. An exception is our BHMF yields a $z=0$ SMBH mass density that is notably higher than the value estimated from quasars at higher redshifts.

[9] 2407.14596

A kiloparsec-scale ordered magnetic field in a galaxy at z=5.6

Magnetic fields are prevalent on almost all astronomical scales, but their importance in different systems and over cosmic time is yet to be understood. Our current knowledge on the evolution of magnetic fields is limited by scarce observations in the distant Universe, where galaxies have recently been found to be more evolved than most of our model predictions. In this study, we conduct rest-frame 131 $\mu$m full-polarisation ALMA observations of dust emission in a strongly lensed dusty star-forming galaxy, SPT0346-52, at z=5.6, when the Universe was only 1 Gyr old. Dust grains can become aligned with local magnetic fields, resulting in the emission of linearly polarised thermal infrared radiation. Our observations have revealed a median polarisation level of 0.9$\pm$0.2 per cent with a variation of $\pm$0.4 per cent across the regions with polarisation detection, similar to that of local starburst galaxies. The polarised dust emission is patchy. It mostly overlaps with the [C II] emission at a velocity of about -150 km/s, and extends over 3 kiloparsecs with a bimodal distribution in position angles. Our analysis indicates that the kpc-scale polarised dust is most likely aligned by the large-scale magnetic fields associated with a galaxy merger. If the ordered fields are confirmed to be coherent, such early detection of large-scale magnetic fields favours an efficient formation of magnetic fields in primordial galaxies, which highlights the importance of magnetic fields in mediating galaxy evolution over long cosmic timescales. Future surveys towards a wider galaxy population are necessary to test the ubiquitousness of large-scale magnetic fields in early galaxies.

[10] 2407.14599

Pumping Iron: How turbulent metal diffusion impacts multiphase galactic outflows

Most numerical simulations of galaxy formation and evolution are unable to properly resolve the turbulent cascade at or below the resolution scale and turbulence models are required to capture the motion of eddies on those unresolved scales. In this study, we investigate the impact of turbulent metal diffusion models on multiphase outflows originating from dwarf galaxies ($M_{\rm halo} \sim 10^{10} - 10^{11}$ M$_\odot$). We use our state-of-the-art numerical model for the formation of single stars and non-equilibrium cooling and hydrogen chemistry. Our simulations are carried out at a mass resolution of $\sim$1 M$_{\odot}$, where the individual supernova explosions are resolved in terms of hot-phase generation and momentum input. We find that mass, energy, and metal loading factors are only weakly affected by the inclusion of a metal diffusion model. The metal enrichment factor at low altitude above the galactic disk is higher by around 20 per cent when the metal diffusion model is included. Specifically, we find more efficient cooling in the cold interstellar medium, as higher amounts of metals are kept in the cold dense phase. The most striking effect of the metal diffusion model is that, without metal diffusion, there is more rapid cooling in the hot phase and a reduced sound speed by a factor of two. Specifically, we find that the hot phase is more metal enriched in the case without metal diffusion leading to more rapid (over) cooling of that phase which is consistent with the higher sound speed we find in the runs with metal diffusion.

[11] 2407.14601

ANDES, the high resolution spectrograph for the ELT: science goals, project overview and future developments

The first generation of ELT instruments includes an optical-infrared high-resolution spectrograph, indicated as ELT-HIRES and recently christened ANDES (ArmazoNes high Dispersion Echelle Spectrograph). ANDES consists of three fibre-fed spectrographs ([U]BV, RIZ, YJH) providing a spectral resolution of $\sim$100,000 with a minimum simultaneous wavelength coverage of 0.4-1.8 $\mu$m with the goal of extending it to 0.35-2.4 $\mu$m with the addition of a U arm to the BV spectrograph and a separate K band spectrograph. It operates both in seeing- and diffraction-limited conditions and the fibre feeding allows several, interchangeable observing modes including a single conjugated adaptive optics module and a small diffraction-limited integral field unit in the NIR. Modularity and fibre-feeding allow ANDES to be placed partly on the ELT Nasmyth platform and partly in the Coud\'e room. ANDES has a wide range of groundbreaking science cases spanning nearly all areas of research in astrophysics and even fundamental physics. Among the top science cases, there are the detection of biosignatures from exoplanet atmospheres, finding the fingerprints of the first generation of stars, tests on the stability of Nature's fundamental couplings, and the direct detection of the cosmic acceleration. The ANDES project is carried forward by a large international consortium, composed of 35 Institutes from 13 countries, forming a team of almost 300 scientists and engineers which include the majority of the scientific and technical expertise in the field that can be found in ESO member states.

[12] 2407.14602

The SHERLOCK pipeline: new exoplanet candidates in the WASP-16, HAT-P-27, HAT-P-26, and TOI-2411 systems

The launches of NASA Kepler and TESS missions have significantly enhanced the interest in the exoplanet field during the last 15 years, providing a vast amount of public data that is being exploited by the community thanks to the continuous development of new analysis tools. However, using these tools is not straightforward, and users must dive into different codes, input-output formats, and methodologies, hindering an efficient and robust exploration of the available data. We present the SHERLOCK pipeline, an end-to-end public software that allows the users to easily explore observations from space-based missions such as TESS or Kepler to recover known planets and candidates issued by the official pipelines and search for new planetary candidates that remained unnoticed. The pipeline incorporates all the steps to search for transit-like features, vet potential candidates, provide statistical validation, conduct a Bayesian fitting, and compute observational windows from ground-based observatories. Its performance is tested against a catalog of known and confirmed planets from the TESS mission, trying to recover the official TESS Objects of Interest (TOIs), explore the existence of companions that have been missed, and release them as new planetary candidates. SHERLOCK demonstrated an excellent performance, recovering 98% of the TOIs and confirmed planets in our test sample and finding new candidates. Specifically, we release four new planetary candidates around the systems WASP-16 (with P$\sim$10.46 d and R$\sim$2.20 $R_\oplus$), HAT-P-27 (with P$\sim$1.20 d and R$\sim$4.33 $R_\oplus$), HAT-P-26 (with P$\sim$6.59 d and R$\sim$1.97 $R_\oplus$), and TOI-2411 (with P$\sim$18.75 d and R$\sim$2.88 $R_\oplus$).

[13] 2407.14604

Gravitational Wave Duet by Resonating Binary Black Holes with Axion-Like Particles

We leverage gravitational wave observations to explore physics beyond the Standard Model, focusing on axion-like particles (ALPs). This study investigates the resonant effects of ALPs with binary black hole systems, where their oscillatory nature induces time-dependent forces on the black holes. By employing a detailed Fisher matrix analysis, we not only probe a new parameter space for ALPs, characterized by their mass and decay constants, but also assess how these parameters affect gravitational waveforms during black hole mergers. Our approach is distinct as it does not assume interactions of ALPs with photons or nucleons. We demonstrate that as binary black holes spiral inward and lose energy, their orbital frequencies may resonate with those of ALPs, producing distinct oscillatory patterns in gravitational waves detectable by upcoming experiments such as the Laser Interferometer Space Antenna (LISA). This work broadens the potential of gravitational wave astronomy as a tool for dark matter searches, offering a promising avenue for studying elusive components of the universe.

[14] 2407.14606

Performance of the Nonlinear Curvature Wavefront Sensor as a Function of Scintillation Strength

Local amplitude aberrations caused by scintillation can impact the reconstruction process of a wavefront sensor (WFS) by inducing a spatially non-uniform intensity at the pupil plane. This effect is especially relevant for the commonly-used Shack-Hartmann WFS (SHWFS), which can lose slope information for portions of the beam where the signal is faint, leading to reduced reconstruction performance and eventually total failure as the level of scintillation increases. An alternative WFS is needed for such conditions. The nonlinear curvature wavefront sensor (nlCWFS) has been shown to achieve better sensitivity compared to the SHWFS under low light levels. Additionally, the nlCWFS has demonstrated the ability to maintain its sensitivity in the presence of scintillation, using amplitude aberrations to help inform the reconstruction process, rather than hinder. Experiments to date have thus far only shown reconstruction results for a single scintillation value. Building upon previous simulations and laboratory experiments, we have built a testbed to quantify the effects of varying scintillation strength on the wavefront reconstruction performance of the nlCWFS compared to an equivalent SHWFS. In this paper, we present results showing the difference in performance between the nlCWFS and SHWFS as a function of relative flux and scintillation strength.

[15] 2407.14611

The Smallsat Technology Accelerated Maturation Platform-1 (STAMP-1): A Proposal to Advance Ultraviolet Science, Workforce, and Technology for the Habitable Worlds Observatory

NASA's Great Observatories Maturation Program (GOMAP) will advance the science definition, technology, and workforce needed for the Habitable Worlds Observatory (HWO) with the goal of a Phase A start by the end of the current decade. GOMAP offers long-term cost and schedule savings compared to the 'TRL 6 by Preliminary Design Review' paradigm historically adopted by large NASA missions. Many of the key technologies in the development queue for HWO require the combined activities of 1) facility and process development for validation of technologies at the scale required for HWO and 2) deployment in the 'real world' environment of mission Integration & Test prior to on-orbit operations. We present a concept for the Smallsat Technology Accelerated Maturation Platform (STAMP), an integrated facility, laboratory, and instrument prototype development program that could be supported through the GOMAP framework and applied to any of NASA's Future Great Observatories (FGOs). This brief describes the recommendation for the first entrant into this program, "STAMP-1", an ESPA Grande-class mission advancing key technologies to enable the ultraviolet capabilities of HWO. STAMP-1 would advance new broadband optical coatings, high-sensitivity ultraviolet detector systems, and multi-object target selection technology to TRL 6 with a flight demonstration. STAMP-1 advances HWO technology on an accelerated timescale, building on current ROSES SAT+APRA programs, reducing cost and schedule risk for HWO while conducting a compelling program of preparatory science and workforce development with direct benefits for HWO mission implementation in the 2030s.

[16] 2407.14615

The Simons Observatory: A Minimum-Cost Matching Algorithm for Pairing Measured Resonances with Designed Detectors

The Simons Observatory (SO) is a ground-based cosmic microwave background experiment currently being deployed to Cerro Toco in the Atacama Desert of Chile. The initial deployment of SO, consisting of three 0.46m-diameter small-aperture telescopes and one 6m-primary large-aperture telescope, will field over 60,000 transition-edge sensors that will observe at frequencies between 30 GHz and 280 GHz. SO will read out its detectors using Superconducting Quantum Interference Device (SQUID) microwave-frequency multiplexing $\mu$mux, a form of frequency division multiplexing where an RF-SQUID couples each TES bolometer to a superconducting resonator tuned to a unique frequency. Resonator frequencies are spaced roughly every 2 MHz between 4 and 6 GHz, allowing for multiplexing factors on the order of 1000. One challenge of $\mu$mux is matching each tracked resonator with its corresponding physical detector. Variations in resonator fabrication, and frequency shifts between cooldowns caused by trapped flux can cause the measured resonance frequencies to deviate significantly from their designed values. In this study, we introduce a method for pairing measured and designed resonators by constructing a bipartite graph based on the two resonator sets, and assigning edge weights based on measured resonator and detector properties such as resonance frequency, detector pointing, and assigned bias lines. Finding the minimum-cost matching for a given set of edge weights is a well-studied problem that can be solved very quickly, and this matching tells us the best assignment of measured resonators to designed detectors for our input parameters. We will present results based on the first on-sky measurements from SAT1, the first SO MF small-aperture telescope.

[17] 2407.14621

Fast and Flexible Inference Framework for Continuum Reverberation Mapping using Simulation-based Inference with Deep Learning

Continuum reverberation mapping (CRM) of active galactic nuclei (AGN) monitors multiwavelength variability signatures to constrain accretion disk structure and supermassive black hole (SMBH) properties. The upcoming Vera Rubin Observatory's Legacy Survey of Space and Time (LSST) will survey tens of millions of AGN over the next decade, with thousands of AGN monitored with almost daily cadence in the deep drilling fields. However, existing CRM methodologies often require long computation time and are not designed to handle such large amount of data. In this paper, we present a fast and flexible inference framework for CRM using simulation-based inference (SBI) with deep learning to estimate SMBH properties from AGN light curves. We use a long-short-term-memory (LSTM) summary network to reduce the high-dimensionality of the light curve data, and then use a neural density estimator to estimate the posterior of SMBH parameters. Using simulated light curves, we find SBI can produce more accurate SMBH parameter estimation with $10^3-10^5$ times speed up in inference efficiency compared to traditional methods. The SBI framework is particularly suitable for wide-field RM surveys as the light curves will have identical observing patterns, which can be incorporated into the SBI simulation. We explore the performance of our SBI model on light curves with irregular-sampled, realistic observing cadence and alternative variability characteristics to demonstrate the flexibility and limitation of the SBI framework.

[18] 2407.14657

Centroiding and Extraction of Tip/Tilt Information from Nonlinear Curvature Wavefront Sensor Measurements

The nonlinear curvature wavefront sensor (nlCWFS) uses multiple (typically four) out-of-focus images to reconstruct the phase and amplitude of a propagating light beam. Because these images are located between the pupil and focal planes, they contain tip/tilt information. Rather than using a separate sensor to measure image locations, it would be beneficial to extract tip/tilt information directly and routinely as part of the reconstruction process. In the presence of atmospheric turbulence, recovering precise centroid offsets for each out-of-focus image becomes a dynamic process as image structure is altered by changing aberrations. We examine several tip/tilt extraction methods and compare their precision and accuracy using numerical simulations. We find that the nlCWFS outer measurement planes confer more accurate and reliable tip/tilt information than the inner measurement planes, due to their larger geometric lever arm. However, in practice, finite field of view (detector region of interest) effects bias tip/tilt retrieval when using the outer planes due to diffraction. Using knowledge of the $z$-distance to each plane, we find that applying a best-fit linear model to multiple image centroid locations can offer fast and accurate tip/tilt mode retrieval. For the most demanding applications, a non-linear tip/tilt extraction method that self-consistently uses the speckle field may need to be developed.

[19] 2407.14677

Simulation results for Robo-AO-2 using HAPA: a wavefront sensing technique for improving the adaptive optics correction of fainter stars

Direct imaging of exoplanets allows us to measure positions and chemical signatures of exoplanets. Given the limited resources for space observations where the atmosphere is absent, we want to make these measurements from the ground. However, it is difficult from the ground because it requires an adaptive optics system to provide an extremely well corrected wavefront to enable coronographic techniques. Currently only natural guide star AO systems have demonstrated the necessary wavefront correction for direct imaging of exoplanets. However, using a stellar source as the guide star for wavefront sensing limits the number of exoplanet systems we can directly image because it requires a relatively bright V~10 mag star. To increase the number of observable targets, we need to push the limit of natural guide stars to fainter magnitudes with high Strehl ratio correction. We propose to combine laser guide star (LGS) and natural guide star (NGS) wavefront sensing to achieve the high Strehl correction with fainter natural guide stars. We call this approach Hybrid Atmospheric Phase Analysis (HAPA); 'hapa' in Hawaiian means 'half' or 'of mixed ethnic heritage'. The relatively bright LGS is used for higher order correction, whereas the NGS is used for high accuracy lower order correction. We focus on demonstrating this approach using Robo-AO-2 at the UH 2.2m telescope on Maunakea with a UV Rayleigh laser at 355 nm. The laser focuses at 10 km altitude and has an equivalent magnitude of m_U~8. In this report specifically, we present simulated results of HAPA employed at Robo-AO-2, with the LGS system having a single configuration of 16x16 subaperture Shack-Hartmann wavefront sensor and the NGS system having 6 different configurations -- 16x16, 8x8, 5x5, 4x4, 2x2 and 1x1. We also discuss the on-sky experiments we plan to carry out with HAPA at the UH 2.2m telescope.

[20] 2407.14702

The factors that influence protostellar multiplicity I: Gas temperature, density, and mass in Perseus with Nobeyama

Protostellar multiplicity is common at all stages and mass ranges. However, the factors that determine the multiplicity of protostellar systems have not been systematically characterized through their molecular gas. Nobeyama 45m Radio Observatory OTF maps of HCN, HNC, HCO$^+$, and N$_2$H$^+$ (J = 1--0) toward five subregions in Perseus, complemented with single pointing APEX observations of HNC (J = 4--3) are used to derive physical parameters of the dense gas. Both observations have angular resolutions of $\sim$18", equivalent to $\sim$5000 AU scales at the distance of Perseus. Kinetic gas temperature is derived from the $I$(HCN)/$I$(HNC) J = 1--0 ratio, and H$_2$ density is obtained from the HNC J=4--3/J=1--0 ratio. These parameters are used to obtain the N$_2$H$^+$ and HCO$^+$ gas masses. The inferred and derived parameters are compared to source parameters. Inferred mean kinetic gas temperature ($I$(HCN)/$I$(HNC) J=1--0 ratio; ranging between 15 and 26 K), and H$_2$ volumetric density (HNC J=4--3/J=1--0; 10$^5$ -- 10$^6$ cm$^{-3}$) do not show correlations with multiplicity in Perseus. The derived gas and dust masses, 1.3 to 16 $\times~10^{-9}$ M$_{\odot}$ for the N$_2$H$^+$ gas mass, 0.1 to 25 M$_{\odot}$ for envelope dust masses (850 $\mu$m), and 0.8 to 10 $\times~10^{-10}$ M$_{\odot}$ for the HCO$^+$ gas mass, are correlated to multiplicity and number of protostellar components. The warm gas masses are a factor of 16 lower than the cold gas masses. This work shows that gas and dust mass is correlated to multiplicity at $\sim$5000 AU scales in Perseus. Higher order multiples tend to have higher gas and dust masses in general, while close binaries (separations $\leq$7") and single protostars have similar gas and dust mass distributions. On the other hand, H$_2$ density and kinetic gas temperature do not show any correlation with multiplicity.

[21] 2407.14711

SO2 and OCS toward high-mass protostars: A comparative study between ice and gas

We investigate the chemical history of interstellar OCS and SO2 by deriving a statistically-significant sample of gas-phase column densities towards massive protostars and comparing to observations of gas and ices towards other sources spanning from dark clouds to comets. We analyze a subset of 26 line-rich massive protostars observed by ALMA as part of the ALMAGAL survey. Column densities are derived for OCS and SO2 from their rare isotopologues O13CS and 34SO2 towards the compact gas around the hot core. We find that gas-phase column density ratios of OCS and SO2 with respect to methanol remain fairly constant as a function of luminosity between low- and high-mass sources, despite their very different physical conditions. The derived gaseous OCS and SO2 abundances relative to CH3OH are overall similar to protostellar ice values, with a significantly larger scatter for SO2 than for OCS. Cometary and dark-cloud ice values agree well with protostellar gas-phase ratios for OCS, whereas higher abundances of SO2 are generally seen in comets compared to the other sources. Gaseous SO2/OCS ratios are consistent with ices toward dark clouds, protostars, and comets, albeit with some scatter. The constant gas-phase column density ratios throughout low and high-mass sources indicate an early stage formation before intense environmental differentiation begins. Icy protostellar values are similar to the gas phase medians, compatible with an icy origin of these species followed by thermal sublimation. The larger spread in SO2 compared to OCS ratios w.r.t. CH3OH is likely due to a more water-rich chemical environment associated with the former, as opposed to a CO-rich origin of the latter. Post-sublimation gas-phase processing of SO2 can also contribute to the large spread. Comparisons to ices in dark clouds and comets point to a significant inheritance of OCS from earlier to later evolutionary stages.

[22] 2407.14723

Prototyping liquid-crystal coronagraphs for exo-Earth imaging

This paper presents initial results from the ESA-funded ``SUPPPPRESS'' project, which aims to develop high-performance liquid-crystal coronagraphs for direct imaging of Earth-like exoplanets in reflected light. The project focuses on addressing the significant challenge of polarization leakage in vector vortex coronagraphs (VVCs). We utilize newly manufactured multi-grating, liquid-crystal VVCs, consisting of a two- or three-element stack of vortex and grating patterns, to reduce this leakage to the $10^{-10}$ contrast level. We detail the experimental setups, including calibration techniques with polarization microscopes and Mueller matrix ellipsometers to enhance the direct-write accuracy of the liquid-crystal patterns. The performance testing of these coronagraph masks will be conducted on the THD2 high-contrast imaging testbed in Paris.

[23] 2407.14753

Optical spectroscopy of 1A 0535+262 before, during, and after the 2020 giant X-ray outburst

We present the findings from our study of the Be/X-ray binary 1A 0535+262/HD 245770 during the giant X-ray outburst in October 2020. We utilized the 1.2-m telescope at Mount Abu Infrared observatory for optical observations of the Be companion star. The outburst reached a peak X-ray flux of approximately 11 Crab in the 15-50 keV range, marking the highest ever recorded X-ray outburst from the pulsar. We conducted optical observations in the 6000-7200 angstrom range before, during, and after the X-ray outburst, aiming to examine the evolution of the circumstellar disc of the Be star from February 2020 to February 2022. Our optical spectra displayed prominent emission lines at 6563 angstrom (H I), 6678 angstrom (He I), and 7065 angstrom (He I). Notably, the H$\alpha$ line exhibited significant variability in the spectra. Prior to and during the outburst, the line profiles appeared single-peaked, and asymmetric with broad red and blue wings, respectively. However, post-outburst observations revealed a double-peaked profile with asymmetry in the blue wing. Our pre-outburst observations confirmed a larger Be circumstellar disc that diminished in size as the outburst progressed. Additionally, the observed variations in the H$\alpha$ line profile and parameters indicate the presence of a highly misaligned, precessing, and warped Be disc.

[24] 2407.14762

Radioactive Gamma-Ray Lines from Long-lived Neutron Star Merger Remnants

The observation of a kilonova AT2017gfo associated with the gravitational wave event GW170817 provides the first strong evidence that neutron star mergers are dominant contributors to the production of heavy $r$-process elements. Radioactive gamma-ray lines emitted from neutron star merger remnants provide a unique probe for investigating the nuclide composition and tracking its evolution. In this work, we studied the gamma-ray line features arising from the radioactive decay of heavy nuclei in the merger remnants based on the $r$-process nuclear reaction network and the astrophysical inputs derived from numerical relativity simulations. The decay chain of $^{126}_{50}$Sn ($T_{1/2}=230$ kyr) $\to$ $^{126}_{51}$Sb ($T_{1/2}=12.35$ days) $\to$ $^{126}_{52}$Te (stable) produces several bright gamma-ray lines with energies of $415$, $667$, and $695$ keV, making it the most promising decay chain during the remnant phase. The photon fluxes of these bright gamma-ray lines reach $\sim10^{-5}$ $\gamma$ cm$^{-2}$ s$^{-1}$ for Galactic merger remnants with ages less than $100$~kyr, which can be detected by the high energy resolution MeV gamma-ray detectors like the MASS mission.

[25] 2407.14807

Spatial distribution of isotopes and compositional mixing in the inner protoplanetary disk

The mass-independent isotopic signatures of planetary bodies have been widely used to trace the mixing and transport processes in planet formation. The observed isotopic variations among meteorites have been further linked to the modeled mass-weighted mean initial semimajor axes, assuming a spatial isotopic gradient in the inner protoplanetary disk. However, nucleosynthetic isotopic anomalies of nonvolatile elements and mass-independent oxygen isotopic variation ($\Delta ^{17}$O) show different relationships with distance from the Sun. Therefore, it is crucial to know whether isotopes were distributed systematically with heliocentric distance. In this study, we performed N-body simulations on compositional mixing during the collisional accretion and migration of planetary bodies to investigate the spatial distributions of Cr and O isotopes in the inner protoplanetary disk. The modeled mass-weighted mean initial semimajor axes of the parent bodies of noncarbonaceous (NC) meteorites and terrestrial planets were used to calculate the isotopic compositions of these bodies. Our simulations successfully reproduced the observed nucleosynthetic Cr isotopic anomaly among Earth, Mars, and the NC meteorite parent bodies, consistent with a spatial gradient of isotopic anomalies in the inner disk. Asteroids originating from different regions in the inner disk were transported to the main belt in our simulations, resulting in the Cr isotopic anomaly variation of the NC meteorite parent bodies. However, the $\Delta ^{17}$O distribution among the terrestrial planets and the NC meteorite parent bodies could not be reproduced assuming a $\Delta ^{17}$O gradient. The absence of a $\Delta ^{17}$O gradient reflects that the oxygen isotopic mass-independent fractionation might have altered the spatial distribution of the nucleosynthetic $\Delta ^{17}$O variation before protoplanets formed.

[26] 2407.14808

Abundances of neutron-capture elements in selected solar-type stars

The primary objective of this study is to accurately determine the abundances of Cu, Sr, Y, Zr, Ba, La, and Ce in selected solar-type stars. This will allow us to establish observational abundance-metallicity and abundance-age relations and to explore the reasons for the excess of Ba compared to other s-elements in younger solar-type stars. We analysed HARPS spectra of main-sequence solar-type FGK stars with metallicities from -0.15 to +0.35 dex and ages from 2 to 14 Gyr using 1D LTE synthesis and MARCS atmospheric models. In the procedure of fitting synthetic to observed line profiles, the free parameters included abundance and microturbulent and macroturbulent velocity. The macroturbulent velocity can substantially compensate for NLTE effects in the line core. We find that the abundance [X/H] increases with metallicity and age. The ratio of the abundances of s-process elements [s/Fe] increases with decreasing metallicity and age, while the [Cu/Fe] ratio increases with both metallicity and age. These observed trends agree well with published observational data and with predictions from Galactic chemical evolution models. A small [Ba/Fe] enhancement of 0.08 +/- 0.08 dex has been detected in seven younger stars with an average age of 2.8 +/- 0.6 Gyr. Compared to the abundances of other s-process elements, [Ba/Fe] is 0.07 and 0.08 dex higher than La and Ce on average, respectively. Furthermore, we find that the [Ba/Fe] ratio increases with increasing chromospheric activity. The average [Ba/Fe] for the three most active stars is 0.15 +/- 0.10 dex higher than that of the other stars. Chromospheric activity can significantly alter the physical conditions in the formation layers of the Ba lines. Our primary conclusion is that to account for the observed excess of [Ba/Fe] abundance in younger stars, it is essential to use more complex atmospheric models that incorporate magnetic structures.

[27] 2407.14817

Accretion regions of meteorite parent bodies inferred from a two-endmember isotopic mixing model

The diverse isotopic anomalies of meteorites demonstrate that the protoplanetary disk was composed of components from different stellar sources, which mixed in the disk and formed the planetary bodies. However, the origin of the accretion materials of different planetary bodies and the cosmochemical relationship between these bodies remain ambiguous. The noncarbonaceous (NC) planetary bodies originate from the inner solar system and have isotopic compositions distinct from those of the carbonaceous (CC) bodies. We combined Ca, Ti, Cr, Fe, Ni, Mo, and Ru isotopic anomalies to develop a quantitative two-endmember mixing model of the NC bodies. Correlations of the isotopic anomalies of different elements with different cosmochemical behaviors originate from the mixing of two common endmembers. Using this mixing model, we calculated the isotopic anomalies of NC bodies for all the considered isotopes, including the isotopic anomalies that are difficult to measure or have been altered by spallation processes. The mixing proportion between the two endmembers in each NC body has been calculated as a cosmochemical parameter, which represents the compositional relationship of the accretion materials between the NC bodies. Using the calculated mixing proportions, the feeding zones of the NC bodies could be estimated. The estimated feeding zones of NC bodies indicate a large population of interlopers in the main asteroid belt and an indigenous origin of Vesta. The feeding zones estimated in different planet formation scenarios indicate that the orbits of Jupiter and Saturn during formation of terrestrial planets were likely to be more circular than their current ones.

[28] 2407.14827

How does the velocity anisotropy of halo stars, dark matter and satellite galaxies depend on host halo properties?

We investigate the mass ($M_{200}$) and concentration ($c_{200}$) dependencies of the velocity anisotropy ($\beta$) profiles for different components in the dark matter halo, including halo stars, dark matter and subhalos, using systems from the IllustrisTNG simulations. Beyond a critical radius, $\beta$ becomes more radial with the increase of $M_{200}$, reflecting more prominent radial accretion around massive halos. The critical radius is $r\sim r_s$, $0.3~r_s$ and $r_s$ for halo stars, dark matter and subhalos, with $r_s$ the scale radius of host halos. This dependence on $M_{200}$ is the strongest for subhalos, and the weakest for halo stars. In central regions, $\beta$ of halo stars and dark matter particles gets more isotropic with the increase of $M_{200}$ in TNG300 due to baryons. By contrast, $\beta$ of dark matter from the dark matter only TNG300-Dark run shows much weaker dependence on $M_{200}$ within $r_s$. Dark matter in TNG300 is slightly more isotropic than in TNG300-Dark at $0.2~r_s<r<10~r_s$ and $\log_{10}M_{200}/M_\odot<13.8$. Halo stars and dark matter also become more radial with the increase in $c_{200}$, at fixed $M_{200}$. Halo stars are more radial than the $\beta$ profile of dark matter by approximately a constant beyond $r_s$. Dark matter particles are more radial than subhalos. The differences can be understood as subhalos on more radial orbits are easier to get stripped, contributing more stars and dark matter to the diffuse components. We provide a fitting formula to the difference between the $\beta$ of halo stars and of dark matter at $r>r_s$ as $\beta_\mathrm{star}-\beta_\mathrm{DM}=(-0.028 \pm 0.008)\log_{10}M_{200}/M_\odot + (0.690\pm0.010)$.

[29] 2407.14830

Metal-silicate mixing in planetesimal collisions

Impacts between differentiated planetesimals are ubiquitous in protoplanetary discs and may mix materials from the core, mantle, and crust of planetesimals, thus forming stony-iron meteorites. The surface composition of the asteroid (16) Psyche represents a mixture of metal and non-metal components. However, the velocities, angles, and outcome regimes of impacts that mixed metal and silicate from different layers of planetesimals are debated. Our aim is to investigate the impacts between planetesimals that can mix large amounts of metal and silicate, and the mechanism of stony-iron meteorite formation. We used smooth particle hydrodynamics to simulate the impacts between differentiated planetesimals with various initial conditions that span different outcome regimes. In our simulations, the material strength was included and the effects of the states of planetesimal cores were studied. Using a statistical approach, we quantitatively analysed the distributions of metal and silicate after impacts. Our simulations modelled the mass, depth, and sources of the metal-silicate mixture in different impact conditions. Our results suggest that the molten cores in planetesimals could facilitate mixing of metal and silicate. Large amounts of the metal-silicate mixture could be produced by low-energy accretional impacts and high-energy erosive impacts in the largest impact remnant, and by hit-and-run and erosive impacts in the second-largest impact remnant. After impact, most of the metal-silicate mixture was buried at depth, consistent with the low cooling rates of stony-iron meteorites. Our results indicate that mesosiderites potentially formed in an erosive impact, while pallasites potentially formed in an accretional or hit-and-run impact. The mixing of metal and non-metal components on Psyche may also be the result of impacts.

[30] 2407.14842

Hydrodynamical simulations of wind interaction in spider systems : A step toward understanding transitional millisecond pulsars

The detected population of "spiders" has significantly grown in the past decade thanks to multiwavelength follow-up investigations of unidentified Fermi sources. These systems consist of low-mass stellar companions orbiting rotation-powered millisecond pulsars in short periods of a few hours up to day. Among them, a subset of intriguing objects called transitional millisecond pulsars (tMSPs) has been shown to exhibit a remarkable behavior, transitioning between pulsar-binary and faint low-mass X-ray binary states over a span of a few years. Our objective is to study the interaction of stellar winds in tMSPs in order to understand their observational properties. To this end we focus on the parameter range that places the system near Roche-lobe overflow. Employing the adaptative mesh refinement (AMR) AMRVAC 2.0 code, we performed 2D hydrodynamical (HD) simulations of the interaction between the flows from both stars, accounting for the effects of gravity and orbital motion. By studying the mass loss and launch speed of the winds, we successfully recreated two phenomenologically distinct regimes: the accretion stream and the radio pulsar state. We also identified the tipping point that marks the sharp transition between these two states. In the pulsar state, we reconstructed the corresponding X-ray light curves of the system that produces the characteristic double-peak pattern of these systems. The position of the peaks is shifted due to orbital motion and the leading peak is weaker due to eclipsing by the companion. We suggest that a smaller leading peak in X-rays is indicative of a nearly edge-on system. This study highlights the importance of gravity and orbital motion in the interaction between the companion and pulsar winds. Our setup allows the study of the complex interaction between the pulsar wind and an accretion stream during mass transfer.

[31] 2407.14856

A physical model for radio and X-ray correlation in black hole X-ray binaries

A tight correlation between the radio and X-ray emission in the hard state of black hole X-ray binaries (BHXRBs) indicates an intrinsic disc-jet connection in stellar black hole accretion systems, though the detailed physics processes at work are still quite unclear. A hot accretion flow is suggested to match the outer cold thin disc at a certain radius in the hard state, which may vary with the accretion rate. In this work, we assume that the magnetic field generated in the outer thin disc is advected inwards by the inner hot accretion flow, which is substantially enhanced near the BH. Such a strong field threading the horizon of a spinning BH is responsible for launching relativistic jets in BHXRBs via the Blandford-Znajek mechanism. Thus, both the jet power and the X-ray emission increase with the mass accretion rate, and we find that our model calculations are able to reproduce the observed radio/X-ray correlation quantitatively. For some individual BHXRBs, the slopes of the radio/X-ray correlations become steeper when the sources are brighter. Our model calculations show that this feature is due to the transition of the outer disc with gas pressure dominated to radiation pressure dominated, which leads to different accretion rate dependence of the field strength in the outer disc.

[32] 2407.14873

Bayesian self-calibration and imaging in Very Long Baseline Interferometry

Self-calibration methods with the CLEAN algorithm have been widely employed in Very Long Baseline Interferometry (VLBI) data processing in order to correct antenna-based amplitude and phase corruptions present in the data. However, human interaction during the conventional CLEAN self-calibration process can impose a strong effective prior, which in turn may produce artifacts within the final image and hinder the reproducibility of final results. In this work, we aim to demonstrate a combined self-calibration and imaging method for VLBI data in a Bayesian inference framework. The method corrects for amplitude and phase gains for each antenna and polarization mode by inferring the temporal correlation of the gain solutions. We use Stokes I data of M87 taken with the Very Long Baseline Array (VLBA) at 43GHz, pre-calibrated using the rPICARD CASA-based pipeline. For antenna-based gain calibration and imaging, we use the Bayesian imaging software resolve. To estimate gain and image uncertainties, we use a Variational Inference method. We obtain a high-resolution M87 Stokes I image at 43GHz in conjunction with antenna-based gain solutions using our Bayesian self-calibration and imaging method. The core with counter-jet structure is better resolved, and extended jet emission is better described compared to the CLEAN reconstruction. Furthermore, uncertainty estimation of the image and antenna-based gains allows us to quantify the reliability of the result. Our Bayesian self-calibration and imaging method is able to reconstruct robust and reproducible Stokes I images and gain solutions with uncertainty estimation by taking into account the uncertainty information in the data.

[33] 2407.14896

Probing 3D magnetic fields using starlight polarization and grain alignment theory

Polarization of starlight induced by dust grains aligned with the magnetic field (hereafter B-field) is widely used to measure the two-dimensional B-fields projected onto the plane-of-sky. Here, we introduce a new method to infer three-dimensional B-fields using starlight polarization. The B-field's inclination angle or line-of-sight (LOS) component of B-fields is constrained by the starlight polarization efficiency from observations and the alignment degree provided by the magnetically enhanced radiative torque (MRAT) alignment theory. We first perform synthetic observation of starlight polarization of magnetohydrodynamic (MHD) simulations of a filamentary cloud. We then test the new technique with our updated POLARIS code and find that the B-field's inclination angles can be precisely determined by the starlight polarization efficiency from synthetic observations. Regardless of grain magnetic properties, the technique can provide an accurate constraint on B-field's inclination angles in low-density regions $N_{\rm H} < 5\times 10^{21}\,\cm^{-2}$ (or visual extinction $A_{V}< 3$) using optical polarization, whereas the technique can infer further to high-density regions $N_{\rm H} \sim 5 \times 10^{22}\,\cm^{-2}$ (or $A_{V}\sim 30$) using near-infrared polarization. Our new technique opens the full potential of tracing 3D B-fields and constraining dust properties and grain alignment physics on multiple scales of the diffuse interstellar medium and star-forming regions using multi-wavelength starlight polarization observations.

[34] 2407.14897

Polarization Patterns of Non-Circular Hotspots around Kerr Black Holes: A Preliminary Study

The multi-wavelength polarized light signals from supermassive black holes have sparked a range of studies on polarized images of accretion disks and hotspots. However, the polarization patterns within the innermost stable circular orbit (ISCO) region remain to be explored. In this study, we focus on two specific types of orbits, namely the plunging geodesics inward from the ISCO and homoclinic geodesics, to uncover the polarization features associated with non-circular motion in a Kerr spacetime. For an on-axis observer, we specifically develop an approximate function to describe gravitational lensing along the azimuthal direction, and establish a simplified synchrotron emission model. Based on these, we analyze the polarized patterns of hotspots accumulated over time and their Stokes parameters. Moreover, we explore the polarized image of the plunging region within a thin accretion disk.

[35] 2407.14930

Athermal package for OH suppression filters in astronomy part 1: design

We present the design of an athermal package for fiber Bragg grating (FBG)filters fabricated at our Institute for use in ground-based near-infrared (NIR) telescopes. Aperiodic multichannel FBG filters combined with photonic lanterns can effectively filter out extremely bright atmospheric hydroxyl (OH) emission lines that severely hinder ground-based NIR observations. While FBGs have the capability of filtering specific wavelengths with high precision, due to their sensitivity to temperature variations, the success in their performance as OH suppression filters depends on a suitable athermal package that can maintain the deviations of the FBG wavelengths from that of the OH emission lines within sub-picometer accuracy over a temperature range of about 40 K. (i.e. 263 K to 303 K). We aim to develop an athermal package over the aforementioned temperature range for an optical fiber consisting of multichannel FBGs for a maximum filter length of 110 mm. In this work, we demonstrate the complete design methodology of such a package. First, we developed a custom-built test rig to study a wide range of critical physical properties of the fiber, such as strain and temperature sensitivities, elastic modulus, optimum fiber pre-tension, and adhesion performance.Next, we used these data to confirm the athermal response of an FBG bonded on the test rig from room temperature to 313 K. Based on this study, we developed a computer-aided design (CAD) model of the package and analyzed its athermal characteristics with a suitable selection of materials and their nominal dimensions using finite element analysis (FEA). We finally discuss the novel aspects of the design to achieve high-precision thermal stabilization of these filters in the temperature range of interest.

[36] 2407.14934

Constraints on interacting dark energy models from the DESI BAO and DES supernovae data

The recent results from the first year baryon acoustic oscillations (BAO) data released by the Dark Energy Spectroscopic Instrument (DESI), combined with cosmic microwave background (CMB) and type Ia supernova (SN) data, have shown a detection of significant deviation from a cosmological constant for dark energy. In this work, we utilize the latest DESI BAO data in combination with the SN data from the full five-year observations of the Dark Energy Survey and the CMB data from the Planck satellite to explore potential interactions between dark energy and dark matter. We consider four typical forms of the interaction term $Q$. Our findings suggest that interacting dark energy (IDE) models with $Q \propto \rho_{\rm de}$ support the presence of an interaction where dark energy decays into dark matter. Specifically, the deviation from $\Lambda$CDM for the IDE model with $Q=\beta H_0\rho_{\rm de}$ reaches the $3\sigma$ level. These models yield a lower value of Akaike information criterion than the $\Lambda$CDM model, indicating a preference for these IDE models based on the current observational data. For IDE models with $Q\propto\rho_{\rm c}$, the existence of interaction depends on the form of the proportionality coefficient $\Gamma$. The IDE model with $Q=\beta H\rho_{\rm c}$ yields $\beta=0.0003\pm 0.0011$, which essentially does not support the presence of the interaction. In general, whether the observational data support the existence of interaction is closely related to the model. Our analysis helps to elucidate which type of IDE model can better explain the current observational data.

[37] 2407.14939

Dynamical dark energy confronted with multiple CMB missions

The measurements of the cosmic microwave background (CMB) have played a significant role in understanding the nature of dark energy. In this article, we investigate the dynamics of the dark energy equation of state, utilizing high-precision CMB data from multiple experiments. We begin by examining the Chevallier-Polarski-Linder (CPL) parametrization, a commonly used and recognized framework for describing the dark energy equation of state. We then explore the general Exponential parametrization, which incorporates CPL as its first-order approximation, and extensions of this parametrization that incorporate nonlinear terms. We constrain these scenarios using CMB data from various missions, including the Planck 2018 legacy release, the Wilkinson Microwave Anisotropy Probe (WMAP), the Atacama Cosmology Telescope (ACT), and the South Pole Telescope (SPT), as well as combinations with low-redshift cosmological probes such as Baryon Acoustic Oscillations (BAO) and the Pantheon sample. While the $\Lambda$CDM cosmology remains consistent within the 68\% confidence level, we observe that the extensions of the CPL parametrization are indistinguishable for Planck data. However, for ACT and SPT data, the inclusion of additional terms begins to reveal a peak in $w_{\rm a, DE}$ that was previously unconstrained.

[38] 2407.14943

Uncertainty of line-of-sight velocity measurement of faint stars from low and medium resolution optical spectra

Massively multiplexed spectrographs will soon gather large statistical samples of stellar spectra. The accurate estimation of uncertainties on derived parameters, such as line-of-sight velocity $v_\mathrm{los}$, especially for spectra with low signal-to-noise ratios, is paramount. We generated an ensemble of simulated optical spectra of stars as if they were observed with low- and medium-resolution fiber-fed instruments on an 8-meter class telescope, similar to the Subaru Prime Focus Spectrograph, and determined $v_\mathrm{los}$ by fitting stellar templates to the simulations. We compared the empirical errors of the derived parameters -- calculated from an ensemble of simulations -- to the asymptotic error determined from the Fisher matrix, as well as from Monte Carlo sampling of the posterior probability. We confirm that the uncertainty of $v_\mathrm{los}$ scales with the inverse square root of $S/N$, but also show how this scaling breaks down at low $S/N$ and analyze the error and bias caused by template mismatch. We outline a computationally optimized algorithm to fit multi-exposure data and provide the mathematical model of stellar spectrum fitting that maximizes the so called significance, which allows for calculating the error from the Fisher matrix analytically. We also introduce the effective line count, and provide a scaling relation to estimate the error of $v_\mathrm{los}$ measurement based on the stellar type. Our analysis covers a range of stellar types with parameters that are typical of the Galactic outer disk and halo, together with analogs of stars in M31 and in satellite dwarf spheroidal galaxies around the Milky Way.

[39] 2407.14973

EPOCHS I. The Discovery and Star Forming Properties of Galaxies in the Epoch of Reionization at $6.5 < z < 18$ with PEARLS and Public JWST data

We present in this paper the discovery, properties, and a catalog of 1165 high redshift $6.5 < z < 18$ galaxies found in deep JWST NIRCam imaging from the GTO PEARLS survey combined with data from JWST public fields. We describe our bespoke homogeneous reduction process and our analysis of these areas including the NEP, CEERS, GLASS, NGDEEP, JADES, and ERO SMACS-0723 fields with over 214 arcmin$^{2}$ imaged to depths of $\sim 30$ mag. We describe our rigorous methods for identifying these galaxies, involving the use of Lyman-break strength, detection significance criteria, visual inspection, and integrated photometric redshifts probability distributions predominately at high redshift. Our sample is a robust and highly pure collection of distant galaxies from which we also remove brown dwarf stars, and calculate completeness and contamination from simulations. We include a summary of the basic properties of these $z > 6.5$ galaxies, including their redshift distributions, UV absolute magnitudes, and star formation rates. Our study of these young galaxies reveals a wide range of stellar population properties as seen in their colors and SED fits which we compare to stellar population models, indicating a range of star formation histories, dust, AGN and/or nebular emission. We find a strong trend exists between stellar mass and $(U-V)$ color, as well as the existence of the `main-sequence' of star formation for galaxies as early as $z \sim 12$. This indicates that stellar mass, or an underlying variable correlating with stellar mass, is driving galaxy formation, in agreement with simulation predictions. We also discover ultra-high redshift candidates at $z > 12$ in our sample and describe their properties. Finally, we note a significant observed excess of galaxies compared to models at $z > 12$, revealing a tension between predictions and our observations.

[40] 2407.14995

First Comparative Exoplanetology Within a Transiting Multi-planet System: Comparing the atmospheres of V1298 Tau b and c

The V1298 Tau system (20-30Myr), is a benchmark young multi-planet system that provides the opportunity to perform comparative exoplanetology between planets orbiting the same star right after their formation. We present the first atmospheric comparison between two planets in the same transiting system: V1298 Tau b and V1298 Tau c. We derive constraints on the mass of planet b and c (<20M$_\oplus$ at 3$\sigma$ confidence level and $17_{-6}^{+13} M_{\oplus}$ respectively) and atmospheric metallicity (logZ/Z$_\odot$=-2.04$_{-0.59}^{0.69}$, -0.16$_{-0.94}^{1.15}$ respectively) from atmospheric retrievals. The V1298 Tau planets, are likely to be similar in terms of mass at the current age, implying that both planets are potential sub-Neptune/super-Earth progenitors. However, planet c is expected to lose a higher fraction of its mass compared to planet b given its close proximity to the host star. Alternatively, the observed spectrum of planet c can be explained by atmospheric hazes, which is in contrast to planet b where efficient haze formation can be ruled out. Higher haze formation efficiency in planet c could be due to differences in atmospheric composition, temperature and higher UV flux incident compared to planet b.

[41] 2407.15005

Gravothermal collapse and the diversity of galactic rotation curves

The rotation curves of spiral galaxies exhibit a great diversity that challenge our understanding of galaxy formation and the nature of dark matter. Previous studies showed that in self-interacting dark matter (SIDM) models with a cross section per unit mass of $\sigma/m\approx{\cal O}(1)~{\rm cm^2/g}$, the predicted dark matter central densities are a good match to the observed densities in galaxies. In this work, we explore a regime with a larger cross section of $\sigma/m\approx20-40~{\rm cm^2/g}$ in dwarf galactic halos. We will show that such strong dark matter self-interactions can further amplify the diversity of halo densities inherited from their assembly history. High concentration halos can enter the gravothermal collapse phase within $10~{\rm Gyr}$, resulting in a high density, while low concentration ones remain in the expansion phase and have a low density. We fit the rotation curves of $14$ representative low surface brightness galaxies and demonstrate how the large range of observed central densities are naturally accommodated in the strong SIDM regime of $\sigma/m\approx20-40~{\rm cm^2/g}$. Galaxies that are outliers in the previous studies due to their high halo central densities, are no longer outliers in this SIDM regime as their halos would be in the collapse phase. For galaxies with a low density, the SIDM fits are robust to the variation of the cross section. Our findings open up a new window for testing gravothermal collapse, the unique signature of strong dark matter self-interactions, and exploring broad SIDM model space.

[42] 2407.15072

Identification of new gold lines in the 350 to 1000 nm spectral region using laser produced plasmas

We present results from a pilot study, using a laser-produced plasma, to identify new lines in the 350 to 1000 nm spectral region for the r-process element gold (Au), of relevance to studies of neutron star mergers. This was achieved via optical-IR spectroscopy of a laser-produced Au plasma, with an Au target of high purity (99.95 %) and a low vacuum pressure to remove any air contamination from the experimental spectra. Our data were recorded with a spectrometer of 750 mm focal length and 1200 lines mm-1 grating, yielding a resolution of 0.04 nm. We find 54 lines not previously identified and which are not due to the impurities (principally copper (Cu) and silver (Ag)) in our Au sample. Of these 54 lines, we provisionally match 21 strong transitions to theoretical results from collisional-radiative models that include energy levels derived from atomic structure calculations up to the 6s level. Some of the remaining 33 unidentified lines in our spectra are also strong and may be due to transitions involving energy levels which are higher-lying than those in our plasma models. Nevertheless, our experiments demonstrate that laser-produced plasmas are well suited to the identification of transitions in r-process elements, with the method applicable to spectra ranging from UV to IR wavelengths.

[43] 2407.15076

Fast radio bursts as precursor radio emission from monster shocks

It has been proposed recently that the breaking of MHD waves in the inner magnetosphere of strongly magnetized neutron stars can power different types of high-energy transients. Motivated by these considerations, we study the steepening and dissipation of a strongly magnetized fast magnetosonic wave propagating in a declining background magnetic field, by means of particle-in-cell simulations that encompass MHD scales. Our analysis confirms the formation of a monster shock as $B^2-E^2 \to 0$, that dissipates about half of the fast magnetosonic wave energy. It also reveals, for the first time, the generation of a high-frequency precursor wave by a synchrotron maser instability at the monster shock front, carrying a fraction of $\sim 10^{-3}$ of the total energy dissipated at the shock. The spectrum of the precursor wave exhibits several sharp harmonic peaks, with frequencies in the GHz band under conditions anticipated in magnetars. Such signals may appear as fast radio bursts.

[44] 2407.15082

Primordial Black Holes and Scalar-induced Gravitational Waves in Sneutrino Hybrid Inflation

We investigate the possibility that primordial black holes (PBHs) can be formed from large curvature perturbations generated during the waterfall phase transition in a supersymmetric scenario where sneutrino is the inflaton in a hybrid inflationary framework. We obtain a spectral index ($n_s \simeq 0.966$), and a tensor-to-scalar ratio ($r\simeq 0.0056-10^{-11}$), consistent with the current Planck data satisfying PBH as dark matter (DM) and detectable Gravitational Wave (GW) signal. Our findings show that the mass of PBH and the peak in the GW spectrum is correlated with the right-handed (s)neutrino mass. We identify parameter space where PBHs can be the entire DM candidate of the universe (with mass $10^{-13}\, M_\odot$) or a fraction of it. This could be tested via second-order GW signals in future observatories, for instance, with amplitude $\Omega_{\rm GW}h^2$ $\sim 10^{-9}$ and peak frequency $f\sim 0.1$ Hz in LISA and $\Omega_{\rm GW}h^2 \sim 10^{-11}$ and peak frequency of $\sim 10$ Hz in ET. %. for sneutrino mass $m_{\phi} \sim 2\times 10^{12}$ GeV, $\beta \sim 5.4\times 10^{15}$ GeV. We study two models of sneutrino inflation: Model$-1$ involves canonical sneutrino kinetic term which predicts the sub-Planckian mass parameter $M$, while the coupling between a gauge singlet and the waterfall field, $\beta$, needs to be quite large whereas, for the model$-2$ involving $\alpha-$attractor canonical sneutrino kinetic term, $\beta$ can take a natural value. Estimating explicitly, we show that both models have mild fine-tuning. We also derive an analytical expression for the power spectrum in terms of the microphysics parameters of the model like (s)neutrino mass, etc. that fits well with the numerical results. The typical reheat temperature for both the models is around $10^{7}-10^{8}$~GeV suitable for non-thermal leptogenesis.

[45] 2407.15093

Ultraviolet Extinction Sky Survey (UVESS): A mission concept for probing the interstellar medium in the Milky Way and Local Group galaxies

The 2175 {\AA} bump shows considerable variations in its strength, width, and central wavelength when observed along different sightlines in the Milky Way and other galaxies. These variations offer valuable insights into the composition, size distribution, and processing of interstellar dust grains along different sightlines. This paper introduces a mission concept called UVESS (Ultraviolet Extinction Sky Survey) aimed at exploring the composition of the interstellar medium (ISM) within both the Milky Way and nearby Local Group Galaxies by mapping the variation of UV extinction curve slopes and the 2175 {\AA} feature across a majority of the sky to gain insights into the makeup of the ISM. Recent advancements in UV instrumentation and technologies pave the way for the development of high-throughput instruments in compact form factors. In this paper, we outline mission science goals and instrument concept tailored for a small satellite-based platform dedicated to the study of UV extinction.

[46] 2407.15117

Profiling stellar environments of gravitational wave sources

Gravitational waves (GWs) have enabled direct detections of compact binary coalescences (CBCs). However, their poor sky localisation and the typical lack of observable electromagnetic (EM) counterparts make it difficult to confidently identify their hosts, and study the environments that nurture their evolution. In this work, we show that $\textit{detailed}$ information of the host environment (e.g. the mass and steepness of the host potential) can be directly inferred by measuring the kinematic parameters (acceleration and its time-derivatives) of the binary's center of mass using GWs alone, without requiring an EM counterpart. We consider CBCs in various realistic environments such as globular clusters, nuclear star clusters, and active galactic nuclei disks to demonstrate how orbit and environment parameters can be extracted for CBCs detectable by ground- and space-based observatories, including the LIGO detector at A+ sensitivity, Einstein Telescope of the XG network, LISA, and DECIGO, $\textit{on a single-event basis}$. These constraints on host stellar environments promise to shed light on our understanding of how CBCs form, evolve, and merge.

[47] 2407.15148

Nonparametric Statistics on Magnetic Properties at the Footpoints of Erupting Magnetic Flux Ropes

It is under debate whether the magnetic field in the solar atmosphere carries neutralized electric currents; particularly, whether a magnetic flux rope (MFR), which is considered the core structure of coronal mass ejections, carries neutralized electric currents. Recently Wang et al. (2023, ApJ, 943, 80) studied magnetic flux and electric current measured at the footpoints of 28 eruptive MFRs from 2010 to 2015. Because of the small sample size, no rigorous statistics has been done. Here, we include 9 more events from 2016 to 2023 and perform a series of nonparametric statistical tests at a significance level of 5\%. The tests confirm that there exist no significant differences in magnetic properties between conjugated footpoints of the same MFR, which justifies the method of identifying the MFR footpoints through coronal dimming. The tests demonstrate that there exist no significant differences between MFRs with pre-eruption dimming and those with only post-eruption dimming. However, there is a medium level of association between MFRs carrying substantial net current and those produce pre-eruption dimming, which can be understood by the Lorentz-self force of the current channel. The tests also suggest that in estimating the magnetic twist of MFRs, it is necessary to take into account the spatially inhomogeneous distribution of electric current density and magnetic field.

[48] 2407.15204

Computational Astrochemistry Journey towards the molecular universe

In astrochemistry, computational methods play a crucial role in addressing fundamental astronomical questions. Interstellar molecules profoundly influence the chemistry and physics of the interstellar medium (ISM), playing pivotal roles in planet formation and the emergence of life. Understanding their chemistry relies on theoretical approaches such as Density Functional Theory (DFT) and post-Hartree-Fock methods, which are essential for exploring pathways to molecular complexity and determining their interstellar abundances. Various theoretical methods investigate the formation of interstellar molecules in both gaseous and solid states. Molecules in interstellar space may originate from bottom-up processes (building up from CO molecules) or top-down processes (polycyclic aromatic hydrocarbon fragmentation). Here, we present a journey of theoretical investigations aimed at studying the reactivity of interstellar molecules in space.

[49] 2407.15263

Crystalline forsterite to 160 GPa: the striking metastability of one of Universe's most abundant minerals

Among Universe's most consequential events are large impacts generating rapidly-evolving extreme pressures and temperatures. Crystalline and amorphous forms of (Mg, Fe)2SiO4 are abundant and widespread, within planets and in space. The behavior of these minerals is expected to deviate form thermodynamic equilibrium in many of the processes that are critical to the formation and evolution of planets, particularly shock events. To further the understanding of the behavior of the silicate under extreme conditions, we statically compressed a crystal of forsterite up to 160.5 GPa, far beyond the compound's stability field, and probed its long-range ordering with synchrotron microdiffraction. We found that forsterite retains long-range ordering up to the highest pressure reached. Forsterite III, emerging at about 58 GPa, persists in compression to 160.5 GPa and in decompression down to about 13 GPa, for a rare combined occurrence of a metastable phase of nearly 150 GPa. These observations dispute earlier reports of pressure-induced amorphization and are a unique testimony of the resilience of the crystalline state in quasi hydrostatic compression. We confirm that highly disordered forsterite can be obtained from the decompression of forsterite III as suggested from the substantial loss of long-range ordering observed at 7 GPa after further decompression. Such kinetic pathway may explain how synthetic olivine glass have been obtained in shock experiments and could be a mechanism of generation of amorphous forsterite in cosmic dust. The 120 GPa Hugoniot discontinuity finds no correspondence in our data, marking a departure from the parallelism between static "cold compression" and dynamic compression.

[50] 2407.15265

Inner dusty regions of protoplanetary discs -- III. The role of non-radial radiation pressure in dust dynamics

We explore dynamical behaviour of dust particles that populate the surface of inner optically thick protoplanetary discs. This is a disc region with the hottest dust and of a great importance for planet formation and dust evolution, but we still struggle to understand all the forces that shape this environment. In our approach we combine results from two separate numerical studies - one is the wind velocity and density distributions obtained from magnetohydrodynamical simulations of accretion discs, and the other is a high-resolution multigrain dust radiation transfer. In our previous paper in the series, we described the methodology for utilising these results as an environmental input for the integration of dust trajectories driven by gravity, gas drag, and radiation pressure. Now we have two improvements - we incorporate time changes in the wind density and velocity, and we implement the non-radial radiation pressure force. We applied our analysis on Herbig Ae and T Tau stars. We confirm that the radiation pressure force can lead to dust outflow, especially in the case of more luminous stars. Additionally, it opposes dust accretion at the inner disc edge and reduces dust settling. These effects are enhanced by the disc wind, especially in the zone where the stellar and the disc magnetic fields meet. Our results suggest that dust grains can stay in the hottest disc region for an extended period and then can end up ejected into the outer disc regions.

[51] 2407.15275

More sulphur in TMC-1: Discovery of the NC$_3$S and HC$_3$S radicals with the QUIJOTE line survey

We present the detection of the free radicals NC$_3$S and HC$_3$S towards TMC-1 with the QUIJOTE line survey. The derived column densities are (1.4$\pm$0.2)$\times$10$^{11}$ for NC$_3$S and (1.5$\pm$0.2)$\times$10$^{11}$ for HC$_3$S. We searched for NCCS, but only three transitions are within the domain of our QUIJOTE line survey and the observed lines are marginally detected at the 3$\sigma$ level, providing an upper limit to its column density of $\leq$6$\times$10$^{10}$ cm$^{-2}$. We also unsuccessfully searched for longer species of the NC$_n$S (n$\ge$4) and HC$_n$S (n$\ge$5) families in our TMC-1 data. A chemical model based on a reduced set of reactions involving HC$_3$S and NC$_3$S predicts abundances that are 10-100 times below the observed values. These calculations indicate that the most efficient reactions of formation of HC$_3$S and NC$_3$S in the model are S + C$_3$H$_2$ and N + HC$_3$S, respectively, while both radicals are very efficiently destroyed through reactions with neutral atoms.

[52] 2407.15279

Strong Observational Support for the R_h=ct Timeline in the Early Universe

JWST's recent discovery of well-formed galaxies and supermassive black holes only a few hundred Myr after the big bang seriously challenges the timeline predicted by $\Lambda$CDM. Now, the latest identification of polycyclic aromatic hydrocarbons (PAHs) at $z=6.71$, together with these earlier inconsistencies, makes the time compression problem in this model quite overwhelming. We consider the timeline associated with the formation and growth of PAH grains based on current astrophysical models and argue that their appearance at $z=6.71$ favors the structure formation history in $R_{\rm h}=ct$ rather than that of Planck-$\Lambda$CDM. We estimate the time at which they must have started growing in each case, and then trace their history through various critical events, such as the end of the `dark ages,' the beginning of Pop III star formation, and the onset of reionization. Together, these three distinct discoveries by JWST, viz. high-$z$ galaxies, high-$z$ quasars and the surprisingly early appearance of PAHs, all paint a fully consistent picture in which the timeline in $\Lambda$CDM is overly compressed at $z\gtrsim 6$, while strongly supporting the expansion history in the early Universe predicted by $R_{\rm h}=ct$.

[53] 2407.15294

Systematic effects induced by half-wave plate differential optical load and TES nonlinearity for LiteBIRD

LiteBIRD, a forthcoming satellite mission, aims to measure the polarization of the Cosmic Microwave Background (CMB) across the entire sky. The experiment will employ three telescopes, Transition-Edge Sensor (TES) bolometers and rotating Half-Wave Plates (HWPs) at cryogenic temperatures to ensure high sensitivity and systematic effects mitigation. This study is focused on the Mid- and High-Frequency Telescopes (MHFT), which will use rotating metal mesh HWPs. We investigate how power variations due to HWP differential emissivity and transmittance combine with TES nonlinear responsivity, resulting in an effective instrumental polarization. We present the results of simulations for the current HWP design, modeling the TES deviation from linearity as a second-order response. We quantify the level of acceptable residual nonlinearity assuming the mission requirement on the tensor-to-scalar ratio, $\delta r < 0.001$. Moreover, we provide an accuracy requirement on the measurement of TES responsivity nonlinearity level for MHFT channels. Lastly, we present possible mitigation methods that will be developed in future studies.

[54] 2407.15303

CORINOS II. JWST-MIRI detection of warm molecular gas from an embedded, disk-bearing protostar

We present James Webb Space Telescope (JWST) Mid-InfraRed Instrument (MIRI) observations of warm CO and H$_2$O gas in emission toward the low-mass protostar IRAS 15398-3359, observed as part of the CORINOS program. The CO is detected via the rovibrational fundamental band and hot band near 5 $\mu$m, whereas the H$_2$O is detected in the rovibrational bending mode at 6-8 $\mu$m. Rotational analysis indicates that the CO originates in a hot reservoir of $1551\pm135$ K, while the water is much cooler at $212\pm 2$ K. Neither the CO nor the H$_2$O line images are significantly spatially extended, constraining the emission to within $\sim$40 au of the protostar. The compactness and high temperature of the CO are consistent with an origin in the embedded protostellar disk, or a compact disk wind. In contrast, the water must arise from a cooler region and requires a larger emitting area (compared to CO) to produce the observed fluxes. The water may arise from a more extended part of the disk, or from the inner portion of the outflow cavity. Thus, the origin of the molecular emission observed with JWST remains ambiguous. Better constraints on the overall extinction, comparison with realistic disk models, and future kinematically-resolved observations may all help to pinpoint the true emitting reservoirs.

[55] 2407.15327

Spectral properties of bright deposits in permanently shadowed craters on Ceres

Bright deposits in permanently shadowed craters on Ceres are thought to harbor water ice. However, the evidence for water ice presented thus far is indirect. We aim to directly detect the spectral characteristics of water ice in bright deposits present in permanently shadowed regions (PSRs) in polar craters on Ceres. We analyzed narrowband images of four of the largest shadowed bright deposits acquired by the Dawn Framing Camera to reconstruct their reflectance spectra, carefully considering issues such as in-field stray light correction and image compression artifacts. The sunlit portion of a polar deposit known to harbor water ice has a negative (blue) spectral slope of $-58 \pm 12$ % $\mu$m$^{-1}$ relative to the background in the visible wavelength range. We find that the PSR bright deposits have similarly blue spectral slopes, consistent with a water ice composition. Based on the brightness and spectral properties, we argue that the ice is likely present as particles of high purity. Other components such as phyllosilicates may be mixed in with the ice. Salts are an unlikely brightening agent given their association with cryovolcanic processes, of which we find no trace. Our spectral analysis strengthens the case for the presence of water ice in permanently shadowed craters on Ceres.

[56] 2407.15386

Super-Earth formation with slow migration from a ring in an evolving peaked disk compatible with terrestrial planet formation

For the origin of the radially concentrated solar system's terrestrial planets, planet formation from a ring of solids at about 1 au from the Sun with convergent/suppressed type I migration is preferred. On the other hand, many super-Earths and sub-Neptunes are found in the close-in region with orbital periods of 10-100 days, so that planet formation from rings in the 1-au region would require some degree of inward migration. One way to realize these different formation scenarios is to use different gas disk models. In this study we investigate whether different scenarios can be realized within a single framework. We consider a disk model that evolves via disk winds and develops a density peak, and study planet formation and orbital evolution using N-body simulations. Planets with masses less than an Earth mass formed from a low-mass ring resembling the solar system do not migrate inward even in the evolving disk and remain near 1-au orbits, maintaining a high radial mass concentration. On the other hand, planets with masses greater than an Earth mass formed from a massive ring slowly migrate inward above the outward migration region. As a result, the innermost planet can move to an orbit of about 10 days. The simulation results also reproduce the characteristics (e.g., mass distribution, eccentricity, orbital separation) of the solar system and super-Earth/sub-Neptune systems. Our model predicts that Earths and sub-Earths formed by migration from rings at near the 1-au region are less abundant in the close-in region.

[57] 2407.15391

Optical alignment of contamination-sensitive Far-Ultraviolet spectrographs for Aspera SmallSat mission

Aspera is a NASA Astrophysics Pioneers SmallSat mission designed to study diffuse OVI emission from the warm-hot phase gas in the halos of nearby galaxies. Its payload consists of two identical Rowland Circle-type long-slit spectrographs, sharing a single MicroChannel plate detector. Each spectrograph channel consists of an off-axis parabola primary mirror and a toroidal diffraction grating optimized for the 1013-1057 Angstroms bandpass. Despite the simple configuration, the optical alignment/integration process for Aspera is challenging due to tight optical alignment tolerances, driven by the compact form factor, and the contamination sensitivity of the Far-Ultraviolet optics and detectors. In this paper, we discuss implementing a novel multi-phase approach to meet these requirements using state-of-the-art optical metrology tools. For coarsely positioning the optics we use a blue-laser 3D scanner while the fine alignment is done with a Zygo interferometer and a custom computer-generated hologram. The detector focus requires iterative in-vacuum alignment using a Vacuum UV collimator. The alignment is done in a controlled cleanroom facility at the University of Arizona.

[58] 2407.15392

Advancing Ultraviolet Detector Technology for future missions: Investigating the dark current plateau in silicon detectors using photon-counting EMCCDs

Understanding the noise characteristics of high quantum efficiency silicon-based ultraviolet detectors, developed by the Microdevices Lab at the Jet Propulsion Laboratory, is critical for current and proposed UV missions using these devices. In this paper, we provide an overview of our detector noise characterization test bench that uses delta-doped, photon counting, Electron-multiplying CCDs (EMCCDs) to understand the fundamental noise properties relevant to all silicon CCDs and CMOS arrays. This work attempts to identify the source of the dark current plateau that has been previously measured with photon-counting EMCCDs and is known to be prevalent in other silicon-based arrays. It is suspected that the plateau could be due to a combination of detectable photons in the tail of blackbody radiation of the ambient instrument, low-level light leaks, and a non-temperature-dependent component that varies with substrate voltage. Our innovative test setup delineates the effect of the ambient environment during dark measurements by independently controlling the temperature of the detector and surrounding environment. We present the design of the test setup and preliminary results.

[59] 2407.15394

A multi-functional fiber positioning system for Extremely Large Telescopes

We present a conceptual design for a fiber positioning system for multi-object high-resolution spectroscopy, designed to be compatible with the upcoming large telescopes with a wide field of view. The design incorporates multiple Atmospheric Dispersion Correctors (ADCs) and tip-tilt mirrors that receive non-telecentric input from individual targets and direct it to the ADCs. Here, we introduce a mechanical design for the fiber positioner that accommodates the optics and operates in a curved focal plane with a Radius of Curvature (R) of 3m. This mechanical design provides four degrees of freedom to access the focal volume, enhancing targeting efficiency. The proposed design and an efficient target allocation algorithm ensure a targeting efficiency of approximately 80-100% for a primary observation session. We also present a methodology for target assignment, positioning, and quantification based on sequential and Monte Carlo (MC) algorithms. This method has been tested on realistic fields with varying target densities to validate its performance.

[60] 2407.15409

Observational Clues to the Magnetic Evolution of Magnetars

Utilizing four archival X-ray datasets taken with the Hard X-ray Detector onboard Suzaku, timing studies were performed on three magnetars, 1E 1841-045 (observed in 2006), SGR 0501+4516 (2008), and 1RXS J170849.0-400910 (2009 and 2010). Their pulsations were reconfirmed, typically in an energy range of 12-50 keV. The 11.783 s pulses of 1E 1841-045, and those of SGR 0501+4516 with 5.762 s were periodically phase modulated, with a long period of about 23.4 ks and about 16.4 ks, respectively. The pulse-phase modulation was also observed, at 46.5 ks, from two datasets of 1RXS J170849.0-400910. In all these cases, the modulation amplitude was 6 to 16 percent of the pulse cycle. Including previously confirmed four objects, this characteristic timing behavior is now detected from seven magnetars in total, and interpreted as a result of free precession of neutron stars that are deformed to an asphericity of ~10^{-4}. Assuming that the deformation is due to magnetic stress, these magnetars are inferred to harbor toroidal magnetic fields of Bt~10^{16} G. By comparing the estimated Bt of these objects with their poloidal dipole field Bd, the Bt/Bd ratio is found to increase with their characteristic age. Therefore, the toroidal fields of magnetars are likely to last longer than their dipole fields. This explains the presence of some classes of neutron stars that have relatively weak Bd but are suspected to hide strong Bt inside them.

[61] 2407.15412

Visible Photonic Lantern integration, characterization and on-sky testing on Subaru/SCExAO

A Photonic Lantern (PL) is a novel device that efficiently converts a multi-mode fiber into several single-mode fibers. When coupled with an extreme adaptive optics (ExAO) system and a spectrograph, PLs enable high throughput spectroscopy at high angular resolution. The Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) system of the Subaru Telescope recently acquired a PL that converts its multi-mode input into 19 single-mode outputs. The single mode outputs feed a R~4,000 spectrograph optimized for the 600 to 760 nm wavelength range. We present here the integration of the PL on SCExAO, and study the device performance in terms of throughput, field of view, and spectral reconstruction. We also present the first on-sky demonstration of a Visible PL coupled with an ExAO system, showing a significant improvement of x12 in throughput compared to the use of a sole single-mode fiber. This work paves the way towards future high throughput photonics instrumentation at small angular resolution.

[62] 2407.15467

FASHI: A blind survey of 21cm HI absorption galaxies with FAST

The FAST All Sky HI survey (FASHI) is broader in frequency band and deeper in detection sensitivity than most of previous HI surveys. FASHI is designed to cover the entire sky observable by the Five-hundred-meter Aperture Spherical radio Telescope (FAST). Based on the FASHI data, we perform a blind survey of 21cm HI absorption galaxies at redshift $z<0.09$ over an area of about 10000 square degrees. We detected 51 HI absorbers, including 21 previously known and 30 new ones, with 8 sources having no optical spectroscopic redshift. The probability of occurrence for HI absorbers in all HI galaxies is 1/1078. The radio flux densities of the FASHI absorbers are mainly concentrated in the range of $S_{\rm 1.4GHz}=10\sim100$ mJy, but even as low as $2.6\pm0.4$mJy. The number of redshifted absorbers is slightly higher than the number of blueshifted absorbers. Such results would provide some important clues for future flux-selected HI absorber surveys. Therefore, FAST has significantly improved the capabilities and performance for HI absorption observations and provided a true blind survey of 21cm HI absorption galaxies for such studies.

[63] 2407.15470

Time Allocation and Long-Term Scheduling of ESO Telescopes at La Silla Paranal Observatory

The preparation of the long-term telescope schedule follows the submission and scientific review of new proposals. At the European Southern Observatory (ESO) this process entails scheduling the scientific proposals according to their scientific merit and available observing resources, as well as scheduling technical, maintenance, and commissioning activities for all operational telescopes of the La Silla Paranal Observatory. After the recent overhaul of the phase 1 proposal submission software, ESO started the development of a new telescopes time allocation and scheduling tool. The new tool makes the scheduling process more efficient while optimising the use of observing facilities. Besides scheduling activities and allocating time according to scientific merit, available resources, operational and programmatic needs, the tool will enable simultaneous scheduling of multiple telescopes to appropriately account for dependencies between them. The implementation of this new Time Allocation tool opens the possibility for dynamic re-scheduling of the telescopes, which is a pre-requisite to implementing a "Yearly Call for Proposals" along with the "Fast Track Channel" at ESO.

[64] 2407.15474

A New Perspective on the Diffuse Gamma-Ray Emission Excess

The Large High-Altitude Air Shower Observatory (LHAASO) recently published measurements of diffuse Galactic gamma-ray emission (DGE) in the 10-1000 TeV energy range. The measured DGE flux is significantly higher than the expectation from hadronic interactions between cosmic rays (CRs) and the interstellar medium. This excess has been proposed to originate from unknown extended sources produced by electron radiation, such as pulsar wind nebulae or pulsar halos (PWNe/halos). In this study, we propose a new perspective to explain the DGE excess observed by LHAASO. The masking regions used in the LHAASO DGE measurement may not fully encompass the extended signals of PWNe/halos. By employing a two-zone diffusion model for electrons around pulsars, we find that the DGE excess in most regions of the Galactic plane can be well explained by the signal leakage model under certain parameters. Our results indicate that the signal leakage from known sources and contributions from unresolved sources should be considered complementary in explaining the DGE excess.

[65] 2407.15477

Evolution of current and pressure driven instabilities in relativistic jets

Instabilities in relativistic magnetized jets are thought to be deeply connected to their energy dissipation properties and to the consequent acceleration of the non-thermal emitting relativistic particles. Instabilities lead to the development of small scale dissipative structures, in which magnetic energy is converted in other forms. In this paper we present three-dimensional numerical simulations of the instability evolution in highly magnetized plasma columns, considering different kinds of equilibria. In fact, the hoop stresses related to the azimuthal component of magnetic field can be balanced either by the magnetic pressure gradient (force-free equilibria, FF) or by the thermal pressure gradient (pressure-balanced equilibria, PB) or by a combination of the two. FF equilibria are prone to current-driven instabilities (CDI), while PB equilibria are prone to pressure-driven instabilities (PDI). We perform a global linear stability analysis, from which we derive the different instability properties in the two regimes, showing that PDI have larger growth rates and are also unstable for high wavenumbers. The numerical simulations of the non-linear instability evolution show similar phases of evolution in which the formation of strong current sheets is followed by a turbulent quasi steady-state. PDI are however characterized by a faster evolution, by the formation of smaller scale dissipative structures and larger magnetic energy dissipation.

[66] 2407.15478

Calibrating Bayesian Tension Statistics using Neural Ratio Estimation

When fits of the same physical model to two different datasets disagree, we call this tension. Several apparent tensions in cosmology have occupied researchers in recent years, and a number of different metrics have been proposed to quantify tension. Many of these metrics suffer from limiting assumptions, and correctly calibrating these is essential if we want to successfully determine whether discrepancies are significant. A commonly used metric of tension is the evidence ratio R. The statistic has been widely adopted by the community as a Bayesian way of quantifying tensions, however, it has a non-trivial dependence on the prior that is not always accounted for properly. We show that this can be calibrated out effectively with Neural Ratio Estimation. We demonstrate our proposed calibration technique with an analytic example, a toy example inspired by 21-cm cosmology, and with observations of the Baryon Acoustic Oscillations from the Dark Energy Spectroscopic Instrument~(DESI) and the Sloan Digital Sky Survey~(SDSS). We find no significant tension between DESI and SDSS.

[67] 2407.15501

Probing the shape of the primordial curvature power spectrum and the energy scale of reheating with pulsar timing arrays

The stochastic gravitational wave background (SGWB) provides a unique opportunity to probe the early Universe, potentially encoding information about the primordial curvature power spectrum and the energy scale of reheating. Recent observations by collaborations such as NANOGrav, PPTA, EPTA+InPTA, and CPTA have detected a stochastic common-spectrum signal, which may originate from scalar-induced gravitational waves (SIGWs) generated by primordial curvature perturbations during inflation. In this study, we explore the hypothesis that the NANOGrav signal is sourced by SIGWs and aim to constrain the shape of the primordial curvature power spectrum and the reheating energy scale using the NANOGrav 15-year data set. We model the primordial curvature power spectrum with a lognormal form and focus on the case where the equation of state during reheating is $w=1/6$, corresponding to an inflaton potential $V(\phi) \sim \phi^{14/5}$. Employing Bayesian inference, we obtain posterior distributions for the lognormal power spectrum parameters and the reheating temperature. Our results indicate a narrow peak in the primordial power spectrum ($\Delta < 0.001$ at 90\% confidence) and a lower bound on the reheating temperature ($T_{\rm rh} \geq 0.1 {\rm GeV}$), consistent with Big Bang Nucleosynthesis constraints. The best-fit SIGW energy density spectrum exhibits a distinct turning point around $f \sim 10^{-8.1}\,{\rm Hz}$, corresponding to the transition from reheating to the radiation-dominated era. This feature, combined with the sharp high-frequency decrease due to the narrow primordial power spectrum peak, offers a unique signature for probing early Universe properties.

[68] 2407.15529

Environmental effects on Low Surface Brightness Galaxies in the IllustrisTNG simulation

Employing the TNG100 run of the IllustrisTNG project, we characterize the environment of Low Surface Brightness Galaxies (LSBGs) across varying scales, from their associated dark matter halos to their distribution within the broader cosmic structure. We find no significant differences in the halo concentration index $c_{200}$ between LSBGs and their High Surface Brightness (HSBGs) counterparts, with LSBGs residing in halos with higher spin parameter $\lambda$ and slightly more spherical shapes than HSBGs. LSBGs show a stronger alignment between the dark and stellar angular momentum vectors than their high surface brightness counterparts. The relative abundance of LSBGs within groups and clusters displays a central deficit, hinting at potential destruction upon reaching these core regions. Studying the density field, we find a preference for rotation-dominated LSBGs to reside in low-density environments, while dispersion-dominated LSBGs thrive in high-density regions where galaxy interactions govern their evolution, an observation corroborated by our analysis of the two-point correlation function $\xi (r)$. Our examination of the cosmic web reveals no significant differences in the distance to the closest large-scale structure, barring a few exceptions. This suggests a limited impact of large-scale spatial distribution on mechanisms driving LSBG evolution. All together, we conclude that the halo vicinity and local environment at the scale of galaxy clusters, where mechanisms such as galaxy mergers and tidal stripping, as well as stellar and gas accretion take place, is the most likely environment that favour the emergence of LSBGs with different morphologies, mostly driven by the presence or absence of important local interaction phenomena.

[69] 2407.15543

Rapid formation of binary asteroid systems post rotational failure: a recipe for making atypically shaped satellites

Binary asteroid formation is a highly complex process, which has been highlighted with recent observations of satellites with unexpected shapes, such as the oblate Dimorphos by the NASA DART mission and the contact binary Selam by NASA's Lucy mission. There is no clear consensus on which dynamical mechanisms determine the final shape of these objects. In turn, we explore a formation pathway where spin-up and rotational failure of a rubble pile asteroid lead to mass-shedding and a wide circumasteroidal debris disk in which the satellite forms. Using a combination of smooth-particle hydrodynamical and N-body simulations, we study the dynamical evolution in detail. We find that a debris disk containing matter corresponding to a few percent of the primary asteroid mass extending beyond the fluid Roche limit can consistently form both oblate and bilobate satellites via a series of tidal encounters with the primary body and mergers with other gravitational aggregates. Principally, satellites end up prolate (elongated) and on synchronous orbits, accreting mainly in a radial direction while tides from the primary asteroid keep the shape intact. However, close encounters and mergers can break the orbital state, leading to orbital migration and deformation. Satellite-satellite impacts occurring in this regime have lower impact velocities than merger-driven moon formation in e.g. planetary rings, leading to soft impacts between differently sized, non-spherical bodies. The resulting post-merger shape of the satellite is highly dependent on the impact geometry. Only moons having experienced a prior mild or catastrophic tidal disruption during a close encounter with the primary asteroid can become oblate spheroids, which is consistent with the predominantly prolate observed population of binary asteroid satellites.

[70] 2407.15544

Shell mergers in the late stages of massive star evolution: new insight from 3D hydrodynamic simulations

One-dimensional (1D) stellar evolution models are widely used across various astrophysical fields, however they are still dominated by important uncertainties that deeply affect their predictive power. Among those, the merging of independent convective regions is a poorly understood phenomenon predicted by some 1D models but whose occurrence and impact in real stars remain very uncertain. Being an intrinsically multi-D phenomenon, it is challenging to predict the exact behaviour of shell mergers with 1D models. In this work, we conduct a detailed investigation of a multiple shell merging event in a 20 M$_\odot$ star using 3D hydrodynamic simulations. Making use of the active tracers for composition and the nuclear network included in the 3D model, we study the merging not only from a dynamical standpoint but also considering its nucleosynthesis and energy generation. Our simulations confirm the occurrence of the merging also in 3D, but reveal significant differences from the 1D case. Specifically, we identify entrainment and the erosion of stable regions as the main mechanisms that drive the merging, we predict much faster convective velocities compared to the mixing-length-theory velocities, and observe multiple burning phases within the same merged shell, with important effects for the chemical composition of the star, which presents a strongly asymmetric (dipolar) distribution. We expect that these differences will have important effects on the final structure of massive stars and thus their final collapse dynamics and possible supernova explosion, subsequently affecting the resulting nucleosynthesis and remnant.

[71] 2407.15553

Cosmological measurement of the gravitational constant $G$ using the CMB

Recent cosmological observations have provided numerous new observations with increasing precision that have led to the era of precision cosmology. The exquisite quality of these observations opens new possibilities towards measuring fundamental constants with good precision and at scales which are complementary to the laboratory ones. In particular, the cosmic microwave background (CMB) temperature and polarization spectra contain a wealth quantity of information, well beyond the basic cosmological parameters. In this paper, we update the precision on a cosmological determination of $G$ by using the latest Planck data release (PR4) in combination with the latest baryon acoustic oscillation (BAO) from the Dark Energy Spectroscopic Instrument (DESI) data release 1. We demonstrate a precision of $2.1\%$, corresponding to a $\sim25\%$ improvement compared to the literature. This measurement is compatible with laboratory ones within one standard deviation. Finally, we show that this cosmological measurement of $G$ is robust against several assumptions made on the cosmological model, in particular when considering a non-standard dark energy fluid or non-flat models.

[72] 2407.15563

Study of consecutive eclipses of pulsar J0024$-$7204O

The eclipses seen in the radio emission of some pulsars can be invaluable to study the properties of the material from the companion stripped away by the pulsar. We present a study of six consecutive eclipses of PSR J0024-7204O in the globular cluster 47 Tucanae as seen by the MeerKAT radio telescope in the UHF (544-1088 MHz) band. A high scintillation state boosted the signal during one of the orbits and allowed a detailed study of the eclipse properties. We measure significant dispersion measure (DM) variations and detect strong scattering that seems to be the dominating mechanism of the eclipses at these frequencies. A complete drop in the linear polarization together with a small increase in the rotation measure suggests the presence of a magnetic field of $\sim 2$ mG. The study of multiple eclipses allowed us to measure difference in the lengths of the eclipses and DM differences of $\sim 0.01$ pc cm$^{-3}$ in consecutive orbits. One orbit in particular shows a delay in recovery of the linear polarization and a visible delay in the arrival of the pulses caused by a stronger scattering event. We suggest that these are caused by a higher variance of density fluctuations during the event.

[73] 2407.15572

FEASTS Combined with Interferometry (II): Significantly Changed HI Surface Densities and Even More Inefficient Star Formation in Galaxy Outer Disks

We update the HI surface density measurements for a subset of 17 THINGS galaxies by dealing with the short-spacing problem of the original VLA HI images. It is the same sample that Bigiel et al. (2010) used to study the relation between HI surface densities and star formation rate surface densities in galaxy outer disks, which are beyond the optical radius r25. For ten galaxies, the update is based on combining original THINGS VLA HI images with HI images taken by the single-dish FAST in the FEASTS program. The median increment of HI surface densities in outer disks is 0.15 to 0.4 dex at a given new HI surface density. Several galaxies change significantly in the shape of radial profiles HI surface densities, and seven galaxies are now more than 1-$\sigma$ below the HI size-mass relation. We update the HI star formation laws in outer disks. The median relation between HI surface densities and star formation rate surface densities based on pixelwise measurements shifts downward by around 0.15 dex because the HI surface density values shift rightward, and the scatter increases significantly. The scatter of the relation, indicating the star forming efficiency, exhibits a much stronger positive correlation with the stellar mass surface density than before. Thus, detecting the previously missed, diffuse HI due to short-spacing problem of the VLA observation is important in revealing the true condition and variation of star formation possibly regulated by stellar feedbacks in localized environment of outer disks.

[74] 2407.15602

Flows, Circulations, and Energy Transport in the Outer and Deep Atmospheres of Synchronous and Non-synchronous Hot Jupiters

Recent studies have shown that vertical enthalpy transport can explain the inflated radii of highly irradiated gaseous exoplanets. They have also shown that rotation can influence this transport, leading to highly irradiated, rapidly rotating, objects that are uninflated. Here we explore the underlying flows, including the impact of (non)synchronous rotation. We use DYNAMICO to run a series of long-timescale, HD209-like, atmospheric models at various surface rotation rates. For models that are tidally-locked, we consider rotation rates between $1/16^\mathrm{th}$ and $40$ times the rotation rate of HD209, whilst for non-synchronous models we consider the range $1/8^\mathrm{th}$ to $4$x. We find that our synchronous models fall into one of three $\Omega$-dependent regimes: at low $\Omega$, we find that the outer atmosphere dynamics are driven by a divergent day-night wind, driving weak vertical transport and the formation of a night-side hot-spot. At intermediate $\Omega$, we find classical hot Jupiter dynamics, whilst at high $\Omega$ we find a strong Coriolis effect that suppresses off-equator dynamics, including the jet-driving standing waves, thus also reducing vertical transport. As for non-synchronicity, when small, we find that it has little effect on dynamics. However as it grows, we find that temporal variations prevents the formation of the persistent structures that drive global dynamics. We find that rotation can significantly impact the atmospheric dynamics of irradiated exoplanets, including vertical advection, which may explain the scatter in the radius-irradiation relation. We have also identified a seemingly robust feature at slow rotation: a night-side hot-spot. As this may have important implications for both the phase curve and atmospheric chemistry, we suggest that this study be followed up with next-generation GCMs that robustly model radiation/chemistry.

[75] 2407.15618

Spectro-temporal investigation of the black hole X-ray transient 4U 1543-475 during the 2021 outburst

We report a detailed spectro-temporal analysis of the black hole (BH) low mass X-ray binary (LMXB) 4U 1543-475 during its 2021 outburst using the data from LAXPC (Large Area X-ray Proportional Counters) and SXT (Soft X-ray Telescope) instrument on board AstroSat. We investigate the energy and frequency dependency of the source variability to probe the origin of the disc/coronal fluctuations. Following the state transition (from soft to intermediate state), the emergence of a band-limited noise (BLN) component is observed along with the power law noise (PLN) when the disk is recovering from a sudden decrease in the inner disk radius. A possible correlation between the low-frequency variability amplitude (RMS) and the covering fraction of the non-thermal component is detected. During the final AstroSat observation, a flip-flop phenomenon is reported, where rapid variation in RMS occurs in concurrence with sudden flux transition. An indication of the evolution of inner disk temperature along with a significant change in thermal flux was observed during the flip-flop phase, arguing for a disk instability-driven origin for this phenomenon. Our results suggest that the long-term variability evolution is primarily affected by the coronal changes, whereas the disk behavior governs the short-term variability evolution.

[76] 2407.15633

Correction to Conversions between gas-phase metallicities in MaNGA

We present a brief correction to Scudder et al. (2021) due to an error in the O3N2 based metallicity calibrations presented in that work. Conclusions are unchanged, but metallicity values shift by $\sim$0.03 dex, with polynomials for affected conversions shifted by the same amount. We present updated materials here.

[77] 2407.15639

Best of both worlds: Fusing hyperspectral data from two generations of spectro-imagers for X-ray astrophysics

With the launch of the X-Ray Imaging and Spectroscopy Mission (XRISM) and the advent of microcalorimeter detectors, X-ray astrophysics is entering in a new era of spatially resolved high resolution spectroscopy. But while this new generation of X-ray telescopes have much finer spectral resolutions than their predecessors (e.g. XMM-Newton, Chandra), they also have coarser spatial resolutions, leading to problematic cross-pixel contamination. This issue is currently a critical limitation for the study of extended sources such as galaxy clusters of supernova remnants. To increase the scientific output of XRISM's hyperspectral data, we propose to fuse it with XMM-Newton data, and seek to obtain a cube with the best spatial and spectral resolution of both generations. This is the aim of hyperspectral fusion. In this article, we have implemented an algorithm that jointly deconvolves the spatial response of XRISM and the spectral response of XMM-Newton. To do so, we construct a forward model adapted for instrumental systematic degradations and Poisson noise, then tackle hyperspectral fusion as a regularized inverse problem. We test three methods of regularization: low rank approximation with Sobolev regularization; low rank approximation with 2D wavelet sparsity ; and 2D-1D wavelet sparsity. We test our method on toy models constructed from hydrodynamic simulations of supernova remnants. We find that our method reconstructs the ground truth well even when the toy model is complex. For the regularization term, we find that while the low rank approximation worked well as a spectral denoiser in models with less spectral variability, it introduced a bias in models with more spectral variability, in which case the 2D-1D wavelet sparsity regularization worked best. After demonstrating a proof of concept in this article, we aim to apply this method to real X-ray astrophysical data in the near future.

[78] 2407.15640

Impacts of dark energy on weighing neutrinos after DESI BAO

Recently, DESI has released baryon acoustic oscillation (BAO) data, and DES has also published its five-year supernova (SN) data. These observations, combined with cosmic microwave background (CMB) data, support a dynamically evolving dark energy at a high confidence level. When using cosmological observations to weigh neutrinos, the results of weighing neutrinos will be significantly affected by the measurement of dark energy due to the degeneracy between neutrino mass and the dark-energy equation of state. Therefore, we need to understand how the dynamical evolution of dark energy in the current situation will affect the measurement of neutrino mass. In this work, we utilize these latest observations and other additional distance measurements to discuss the mutual influence between neutrinos and dark energy, then calculate the Bayes factor to compare models. We consider three neutrino mass hierarchies including degenerate hierarchy (DH), normal hierarchy (NH), and inverted hierarchy (IH), as well as three dark energy models including $\Lambda \rm CDM$, $w\rm CDM$, and $w_0w_a \rm CDM$ models. Cosmological data combined with the prior of particle physics experiments can provide strong to decisive evidence favoring the $w_0w_a {\rm CDM}+\sum m_\nu$ model with NH. In the $w_0w_a \rm CDM$ model, using the CMB+DESI+DESY5 data, we obtain constraints on the total neutrino mass, $\sum m_\nu<0.171\ \rm eV,\ 0.204\ \rm eV,\ 0.220\ \rm eV$, for DH, NH, and IH, respectively. Furthermore, taking into account the neutrino hierarchy or incorporating additional distance measurements results in a more pronounced deviation from the $\Lambda$CDM model for dark energy. The latter, particularly, exhibits a deviation at a confidence level that surpasses $4\sigma$.

[79] 2407.15655

Imprint of the magnetic activity cycle on solar asteroseismic characterisation based on 26 years of GOLF and BiSON data

Building on the success of previous missions, asteroseismic modelling will play a key role in future space-based missions, such as PLATO, CubeSpec, and Roman. Despite remarkable achievements, asteroseismology has revealed significant discrepancies in the physics of theoretical stellar models, which have the potential to bias stellar characterisation at the precision level demanded by PLATO. The current modelling strategies largely overlook magnetic activity, assuming that its effects are masked by filtering the so-called surface effects. Given the presence of activity cycles in multiple solar-like oscillators, and activity variations in a significant fraction of Kepler observations of main-sequence stars (Santos et al. 2019b, 2021, 2023), we measured the impact of magnetic activity on the asteroseismic characterisation of the Sun based on 26.5 years of GOLF and BiSON observations. While magnetic activity is partially absorbed in the treatment of surface effects, we found a discernible imprint of the activity cycle in the determination of the solar age. Notably, this imprint persists across both BiSON and GOLF datasets, with significant variations of up to 6.5% observed between solar minima and maxima. Considering that the Sun exhibits low levels of activity, our study underscores the looming challenge posed by magnetic activity for future photometry missions, and prompts a potential reevaluation of the asteroseismic characterisation of Kepler's most active targets.

[80] 2407.15732

A fast frequency-domain expression for the time-dependent detector response of ground-based gravitational-wave detectors to compact binary signals

For proposed third-generation gravitational-wave detectors such as the Einstein Telescope and Cosmic Explorer, whose sensitive bands are proposed to extend down to 5 Hz or below, the signals of low-mass compact binaries such as binary neutron stars remain in the detector's sensitive band long enough (up to a few days for the smallest proposed low-frequency cutoff of 1 Hz) that one cannot neglect the effects of the Earth's rotation on the detector's response and the changing Doppler shift of the signal. In the latter case, one also needs to consider the effects of the Earth's orbital motion, which is currently only included in analyses of compact binary signals using continuous wave techniques. These effects are also relevant for current detectors and signals from putative subsolar-mass binaries. Here we present simple Fourier series methods for computing these effects in the frequency domain, giving explicit expressions for the Earth's orbital motion in terms of low-order Fourier series, which will be sufficiently accurate for all compact binary signals except for those from very low-mass subsolar-mass binaries. The expression for the effects of the Earth's rotation on the antenna pattern functions does not use the stationary phase approximation (SPA), so we are able to show that the SPA is indeed quite accurate in these situations and present a Fourier series expression equivalent to it which is an order of magnitude faster. We also provide illustrations of these effects on detector sensitivity and the accumulation of information about various binary parameters with frequency.

[81] 2407.15767

Reinterpretation of the Fermi acceleration of cosmic rays in terms of the ballistic surfing acceleration in supernova shocks

The applicability of first-order Fermi acceleration in explaining the cosmic ray spectrum has been reexamined using recent results on shock acceleration mechanisms from the Multiscale Magnetospheric mission in Earth's bow shock. It is demonstrated that the Fermi mechanism is a crude approximation of the ballistic surfing acceleration (BSA) mechanism. While both mechanisms yield similar expressions for the energy gain of a particle after encountering a shock once, leading to similar power-law distributions of the cosmic ray energy spectrum, the Fermi mechanism is found to be inconsistent with fundamental equations of electrodynamics. It is shown that the spectral index of cosmic rays is determined by the average magnetic field compression rather than the density compression, as in the Fermi model. It is shown that the knee observed in the spectrum at an energy of 5x10^{15} eV could correspond to ions with a gyroradius comparable to the size of shocks in supernova remnants. The BSA mechanism can accurately reproduce the observed spectral index s = -2.5 below the knee energy, as well as a steeper spectrum, s = -3, above the knee. The acceleration time up to the knee, as implied by BSA, is on the order of 300 years. First-order Fermi acceleration does not represent a physically valid mechanism and should be replaced by ballistic surfing acceleration in applications or models related to quasi-perpendicular shocks in space. It is noted that BSA, which operates outside of shocks, was previously misattributed to shock drift acceleration (SDA), which operates within shocks.

[82] 2407.15768

Early-Time Observations of SN 2023wrk: A Luminous Type Ia Supernova with Significant Unburned Carbon in the Outer Ejecta

We present extensive photometric and spectroscopic observations of the nearby Type Ia supernova (SN) 2023wrk at a distance of about 40 Mpc. The earliest detection of this SN can be traced back to a few hours after the explosion. Within the first few days the light curve shows a bump feature, while the B - V color is blue and remains nearly constant. The overall spectral evolution is similar to that of an SN 1991T/SN 1999aa-like SN Ia, while the C II $\lambda6580$ absorption line appears to be unusually strong in the first spectrum taken at $t \approx -$15.4 days after the maximum light. This carbon feature disappears quickly in subsequent evolution but it reappears at around the time of peak brightness. The complex evolution of the carbon line and the possible detection of Ni III absorption around 4700 {\AA} and 5300 {\AA} in the earliest spectra indicate macroscopic mixing of fuel and ash. The strong carbon lines is likely related to collision of SN ejecta with unbound carbon, consistent with the predictions of pulsational delayed-detonation or carbon-rich circumstellar-matter interaction models. Among those carbon-rich SNe Ia with strong C II $\lambda6580$ absorption at very early times, the line-strength ratio of C II to Si II and the B-V color evolution are found to exhibit large diversity, which may be attributed to different properties of unbound carbon and outward-mixing $^{56}$Ni.

[83] 2407.15781

High-redshift JWST massive galaxies and the initial clustering of supermassive primordial black holes

In this paper, we show that the initial clustering of supermassive primordial black holes (SMPBHs) beyond a Poisson distribution can efficiently enhance the matter power spectrum, and thus the halo mass function. As a result, the population of initially clustered SMPBHs with $M_{\rm PBH}\sim 10^9M_\odot$ and the fraction of energy density $f_{\rm PBH}\sim 10^{-3}$ (consistent with current constraints on SMPBHs) has the potential to naturally explain high-redshift massive galaxies observed by the James Webb Space Telescope.

[84] 2407.15800

The Evaporating Massive Embedded Stellar Cluster IRS 13 Close to Sgr A*. II. Kinematic structure

The existence of two distinct and apparently unrelated populations of dusty stellar objects in the Nuclear Stellar Cluster (NSC) of the Milky Way, namely IRS 13 and the S-cluster, are potentially prone to a general process describing the star formation history in the Galactic Center (GC). The former cluster is thought to be entangled in the clockwise and counterclockwise disks, a large-scale stellar distribution revealed by the analysis of stars at different distances from Sgr A*, the supermassive black hole in the GC. Recently, this large-scale distribution was reported to exhibit a multi-disk structure with at least four components. Motivated by this finding, we revisit the anisotropic IRS 13 cluster and find strong evidence for a disk-like structure. An examination of about 50 individual stellar orbits reveals a new structure that does not follow any trend known in the literature. Furthermore, we investigate the possibility of an inspiral cluster undergoing star formation processes, as proposed by several authors. Using a simplified N-body simulation to reproduce our observational results, we conclude that, under certain conditions, a massive cluster can migrate from the Circum Nuclear Disk toward the inner parsec. Based on this classification, we revisit the large-scale NACO (VLT) observations of IRS 13 and find evidence for a separation of the cluster into a gravitationally stable core remnant and a dissipating part. With the velocity-resolved H30{\alpha} line and the broadband spectral energy distribution of IRS 13E3, we provide tentative support for the existence of an intermediate-mass black hole of ~ 3 x 10^26 M_sun surrounded by a hot gaseous stream.

[85] 2407.15807

A biconical ionised gas outflow and evidence for positive feedback in NGC 7172 uncovered by MIRI/JWST

We present observations of the type-2 Seyfert NGC7172 obtained with the medium-resolution spectrometer (MRS) of the Mid-Infrared Instrument (MIRI) on board of the JWST. This galaxy hosts one of the lowest ionised gas mass outflow rates (Mout~0.005 M/yr) in a sample of six AGN with similar bolometric luminosities (log Lbol~44erg/s) within the Galactic Activity, Torus and Outflow Survey (GATOS). We aim to understand the properties of the ionised gas outflow, mainly using the emission lines from the neon transitions, that cover a broad range of ionisation potentials (IP) from ~20 eV to ~130 eV. We applied parametric and non-parametric methods to characterise the line emission and kinematics. The low excitation lines (IP<25eV, e.g.[NeII]) trace the rotating disc emission. The high excitation lines (IP>90eV, e.g.[NeV]), which are likely photoionised exclusively by the AGN, are expanding in the direction nearly perpendicular to the disc of the galaxy, with maximum projected velocities of ~350-500 km/s. In particular, [NeV] and [NeVI] lines reveal a biconical ionised gas outflow emerging N-S from the nuclear region, extending at least ~2.5"N and 3.8"S (projected distance of ~450 and 680 pc). Most of the emission arising in the northern part of the cone was not previously detected due to obscuration. Given the almost face-on orientation of the outflow and the almost edge-on orientation of the galaxy, NGC7172 may be a case of weak coupling. Nevertheless, we found evidence for positive feedback in two distinct outflowing clumps at projected distances of 3.1" and 4.3" (i.e. ~560 and 780 pc) SW from the AGN. We estimated a star formation rate in these regions using the [NeII] and [NeIII] luminosities of 0.08 M/yr, that is ~10% of that found in the circumnuclear ring. The star formation activity might have been triggered by the interaction between the ionised gas outflow and the ISM of the galaxy.

[86] 2407.15824

Unveiling the Multifaceted GRB 200613A: Prompt Emission Dynamics, Afterglow Evolution, and the Host Galaxy's Properties

We present our optical observations and multi-wavelength analysis of the GRB\,200613A detected by \texttt{Fermi} satellite. Time-resolved spectral analysis of the prompt $\gamma$-ray emission was conducted utilizing the Bayesian block method to determine statistically optimal time bins. Based on the Bayesian Information Criterion (BIC), the data generally favor the Band+Blackbody (short as BB) model. We speculate that the main Band component comes from the Blandford-Znajek mechanism, while the additional BB component comes from the neutrino annihilation process. The BB component becomes significant for a low-spin, high-accretion rate black hole central engine, as evidenced by our model comparison with the data. The afterglow light curve exhibits typical power-law decay, and its behavior can be explained by the collision between the ejecta and constant interstellar medium (ISM). Model fitting yields the following parameters: $E_{K,iso} = (2.04^{+11.8}_{-1.50})\times 10^{53}$ erg, $\Gamma_0=354^{+578}_{-217}$, $p=2.09^{+0.02}_{-0.03}$, $n_{18}=(2.04^{+9.71}_{-1.87})\times 10^{2}$ cm$^{-3}$, $\theta_j=24.0^{+6.50}_{-5.54}$ degree, $\epsilon_e=1.66^{+4.09}_{-1.39})\times 10^{-1}$ and $\epsilon_B=(7.76^{+48.5}_{-5.9})\times 10^{-6}$. In addition, we employed the public Python package \texttt{Prospector} perform a spectral energy distribution (SED) modeling of the host galaxy. The results suggest that the host galaxy is a massive galaxy ($\log(M_\ast / M_\odot)=11.75^{+0.10}_{-0.09}$) with moderate star formation rate ($\mbox{SFR}=22.58^{+13.63}_{-7.22} M_{\odot}$/yr). This SFR is consistent with the SFR of $\sim 34.2 M_{\odot}$ yr$^{-1}$ derived from the [OII] emission line in the observed spectrum.

[87] 2407.15826

Statistics and Habitability of F-type Star--Planet Systems

F-type star--planet systems represent an intriguing case for habitability studies. Although F-type stars spend considerably less time on the main-sequence than G, K, and M-type stars, they still offer a unique set of features, allowing for the principal possibility of exolife. Examples of the latter include the increased widths of stellar habitable zones as well as the presence of enhanced UV flux, which in moderation may have added to the origin of life in the Universe. In this study, we pursue a detailed statistical analysis of the currently known planet-hosting F-type stars by making use of the NASA Exoplanet Archive. After disregarding systems with little or no information on the planet(s), we identify 206 systems of interest. We also evaluate whether the stars are on the main-sequence based on various criteria. In one approach, we use the stellar evolution code MESA. Depending on the adopted criterion, about 60 to 80 stars have been identified as main-sequence stars. In 18 systems, the planet spends at least part of its orbit within the stellar habitable zone. In one case, i.e., HD 111998, commonly known as 38 Vir, the planet is situated in the habitable zone at all times. Our work may serve as a basis for future studies, including studies on the existence of Earth-mass planets in F-type systems, as well as investigations of possibly habitable exomoons hosted by exo-Jupiters as the lowest-mass habitable zone planet currently identified has a mass estimate of 143 Earth masses.

[88] 2407.15832

Non-minimally coupled gravity as a physically viable fit to DESI 2024 BAO

The recent measurements of baryon acoustic oscillations (BAO) from the DESI collaboration have presented an indication for dynamical dark energy, when adopting the $(w_0,w_a)$ parametrization of the equation of state. The associated posterior constraints imply a crossing of the phantom divide. The latter, however, has profound theoretical implications because not all models can do so without developing incurable instabilities. Simple quintessence models of dark energy, for instance, would be ruled out if such a crossing is confirmed. We perform a non-parametric reconstruction of the equation of state, and confirm that crossing of the phantom divide is required by the DESI BAO data. We then explore the theory space of Horndeski gravity employing a reconstruction method based on the effective field theory of dark energy, and show that for most of the models it is still difficult to safely cross the divide. We identify non-minimal coupling to gravity as the key modification which sustains a stable phantom crossing in the general Horndeski theory space and fits DESI observations. Guided by these insights, we propose the \textit{Thawing Gravity} model which has the same number of parameters as $w_0w_a$CDM and naturally realizes non-minimal coupling when dark energy becomes non-negligible. \textit{Thawing Gravity} improves the fit over $\Lambda$CDM for DESI BAO, CMB as well as type Ia Supernovae.

[89] 2407.15846

ALESS-JWST: Joint (sub-)kiloparsec JWST and ALMA imaging of $z\sim3$ submillimeter galaxies reveals heavily obscured bulge formation events

We present JWST NIRCam imaging targeting 13 $z\sim3$ infrared-luminous ($L_{\rm IR}\sim5\times10^{12}L_{\odot}$) galaxies from the ALESS survey with uniquely deep, high-resolution (0.08$''$$-$0.16$''$) ALMA 870$\mu$m imaging. The 2.0$-$4.4$\mu$m (observed frame) NIRCam imaging reveals the rest-frame near-infrared stellar emission in these submillimeter-selected galaxies (SMGs) at the same (sub-)kpc resolution as the 870$\mu$m dust continuum. The newly revealed stellar morphologies show striking similarities with the dust continuum morphologies at 870$\mu$m, with the centers and position angles agreeing for most sources, clearly illustrating that the spatial offsets reported previously between the 870$\mu$m and HST morphologies were due to strong differential dust obscuration. The F444W sizes are 78$\pm$21% larger than those measured at 870$\mu$m, in contrast to recent results from hydrodynamical simulations that predict larger 870$\mu$m sizes. We report evidence for significant dust obscuration in F444W for the highest-redshift sources, emphasizing the importance of longer-wavelength MIRI imaging. The majority of the sources show evidence that they are undergoing mergers/interactions, including tidal tails/plumes -- some of which are also detected at 870$\mu$m. We find a clear correlation between NIRCam colors and 870$\mu$m surface brightness on $\sim$1 kpc scales, indicating that the galaxies are primarily red due to dust -- not stellar age -- and we show that the dust structure on $\sim$kpc-scales is broadly similar to that in nearby galaxies. Finally, we find no strong stellar bars in the rest-frame near-infrared, suggesting the extended bar-like features seen at 870$\mu$m are highly obscured and/or gas-dominated structures that are likely early precursors to significant bulge growth.

[90] 2407.14523

Spinel-Bearing Spherules Condensed from the Chicxulub Impact-Vapor Plume

Formation of the giant Chicxulub crater off Mexico's Yucatan Peninsula coincided with deposition of the global Ir-rich Cretaceous-Tertiary (K-T) stratigraphic boundary layer at ca. 65 Ma. The boundary is marked most sharply by abundant spherules containing unaltered grains of magnesioferrite spinel. Here we predict for the first time the sequential condensation of solids and liquids from the plume of vaporized rock expected from oblique K-T impacts. We predict highly oxidizing plumes that condense silicate liquid droplets bearing spinel grains whose compositions closely match those marking the actual boundary. Systematic global variations in spinel composition are consistent with higher condensation temperatures for spinels found at Atlantic and European sites than for those in the Pacific.

[91] 2407.14549

Black hole event horizons are cosmologically coupled

It is shown that an exactly static black hole event horizon cannot be embedded in a time-dependent geometry. Forcing it to do so results in a naked null singularity at the would-be horizon. Therefore, since the universe is expanding, black holes must couple to the cosmological expansion, which was suggested as the growth mechanism for supermassive black holes in galaxies, with implications for the dark energy puzzle.

[92] 2407.14592

Scalar Dark Matter Production through the Bubble Expansion Mechanism: The Boosting Role of Non-Renormalizable Interactions

We consider a Bubble Expansion mechanism for the production of scalar dark matter during a first-order phase transition in the early Universe. Seeking for a dark matter energy density in agreement with observations, we study different non-renormalizable interactions between the dark matter species and the field undergoing the transition. The resulting relic abundance is shown to display a strong dependence on the Lorentz boost factor associated to the bubble wall motion, with this dependence becoming more significant the higher the dimension of the non-renormalizable interaction. This allows for observational compatibility across a wide range of dark matter masses and transition temperatures, typically excluded in renormalizable scenarios. For a transition around the electroweak scale, the associated gravitational wave spectrum is also within the reach of future detectors.

[93] 2407.14598

The Non-Relativistic Effective Field Theory Of Dark Matter-Electron Interactions

Electronic excitations in atomic, molecular, and crystal targets are at the forefront of the ongoing search for light, sub-GeV dark matter (DM). In many light DM-electron interactions the energy and momentum deposited is much smaller than the electron mass, motivating a non-relativistic (NR) description of the electron. Thus, for any target, light DM-electron phenomenology relies on understanding the interactions between the DM and electron in the NR limit. In this work we derive the NR effective field theory (EFT) of general DM-electron interactions from a top-down perspective, starting from general high-energy DM-electron interaction Lagrangians. This provides an explicit connection between high-energy theories and their low-energy phenomenology in electron excitation based experiments. Furthermore, we derive Feynman rules for the DM-electron NR EFT, allowing observables to be computed diagrammatically, which can systematically explain the presence of in-medium screening effects in general DM models. We use these Feynman rules to compute absorption, scattering, and dark Thomson scattering rates for a wide variety of high-energy DM models.

[94] 2407.14603

Implications of Sgr A$^\ast$ on the $γ$-rays searches of Bino Dark Matter with $(g-2)_μ$

We analyse the impact of dark matter density spike around the Milky Way's supermassive black hole (SMBH), Sgr A$^*$, in probing the Bino-dominated neutralino dark matter (DM) $\tilde \chi_1^0$ within the MSSM, which typically produces relatively faint signals in the conventional DM halos. In particular, we explore the indirect search prospects of sub-TeV Bino-Higgsino and Bino-Wino-Higgsino DM in the MSSM, consistent with the supersymmetric predictions required to explain the anomalous magnetic moment of the muon. Typical over-abundance of Bino DM is ameliorated with slepton and/or Wino coannihilations. The lightest neutralino, thus, may be associated with a compressed supersymmetric particle spectrum, which, in general, is difficult to probe at conventional LHC searches. Similarly, for a rather tiny Higgsino mixing, $\tilde \chi_1^0$ does not offer much prospect to assess its predictions at dark matter direct detection searches. Accommodating the inclusive effects of density spike, here, we present the requisite boost factor to facilitate $\gamma-$ray searches of Bino-dominated DM in the MSSM, especially focusing on the Fermi-LAT and HESS observations.

[95] 2407.14629

Astronomy's relationship with the lands and communities of Maunakea

Astronomy is at a turning point in its history and in its relations with the Indigenous peoples who are the generational stewards of land where several of our main observatories are located. The controversy regarding the further development of astronomy facilities on Maunakea is probably the most significant and publicized conflict about the use of such land in the name of science. Thousands have stood in resistance, elders were arrested, and the community is divided. Astronomy's access to one of its most emblematic sites is at risk. This situation challenges our professional practice, the projects we build on Indigenous lands, and our relationships with the people who live within these lands and with society in general. This paper attempts to share the perspective of the authors on the historical events, including the very recent past, through the lens of our understanding and opinions; to provide transparency, with humility, into our process of introspection and transformation; and to share our hopes and ambitions as leaders from Maunakea Observatories for the future of astronomy in Hawai'i, as advocated by the Astro2020 report from the U.S. National Academies of Sciences, Engineering, and Medicine; and to suggest ways for the profession to commit to this long-term vision.

[96] 2407.14810

The Role of Helical and Non-Helical Drives on the evolution of Self-Consistent Dynamos

In the self-consistent dynamo limit, the magnetic feedback on the velocity field is sufficiently strong to induce a change in the topology of the magnetic field. Consequently, the magnetic energy reaches a state of non-linear saturation. Here, we investigate the role played by helical and non-helical drives in the triggering and the eventual saturation of a self-consistent dynamo. Evidence of small-scale dynamo (SSD) activity is found for both helical and non-helical forcing, driven at the largest possible scale. Based on the spectrum analysis, we find that the evolution of kinetic energy follows Kolmogorov's $k^-{\frac{5}{3}}$ law while that of magnetic energy follows Kazantsev's $k^{\frac{3}{2}}$ scaling. Also, we have verified that the aforementioned scalings remain valid for various magnetic Prandtl numbers (Pm). Statistical analysis is found to support our numerical finds.

[97] 2407.14851

Observational and theoretical aspects of Superspinars

This article delves into the observational signatures and theoretical underpinnings of rotating astrophysical objects, with a particular focus on superspinars -exotic objects characterized by preventing the formation of event horizons due to their high angular momentum. While solutions within General Relativity (Kerr superspinars) predict such objects, their classical forms harbor naked singularities, violate causality, and exhibit problematic repulsive gravitational effects. These characteristics render classical superspinars theoretically objectionable, leading to the consideration of them as physically implausible. On the other hand, the incompatibility between General Relativity and Quantum Mechanics suggests the exploration of alternative models, particularly those in which Quantum Gravity dominates the core, yielding regular superspinars. This work demonstrates that regular superspinars avoid all the complications associated with Kerr superspinars. From a phenomenological standpoint, it is shown that the silhouettes of regular superspinars are markedly distinct from those of black holes and classical Kerr superspinars. To substantiate these differences, we perform a comprehensive analysis of inner null geodesics and investigate the structure of the Planckian region within regular superspinars. Our study reveals that only regular superspinars provide the potential for distant observers to directly observe the extremely high curvature regions within their interiors.

[98] 2407.15069

Dipole Cosmology in $f(Q)$-gravity

Symmetric teleparallel $f(Q)$-gravity allows for the presence of a perfect fluid with a tilted velocity in the Kantowski-Sachs geometry. In this dipole model, we consider an ideal gas and we investigate the evolution of the physical parameters. The tilt parameter is constrained by the nonlinear function $f(Q)$ through the non-diagonal equations of the field equations. We find that the dynamics always reduce to the vacuum solutions of STEGR. This includes the Kasner universe, when no cosmological term is introduced by the $f(Q)$ function, and the isotropic de Sitter universe, where $f\left( Q\right) $ plays the role of the cosmological constant. In the extreme tilt limit, the universe is consistently anisotropic and accelerated. However, the final solution matches that of STEGR.

[99] 2407.15347

Energy extraction through Comisso-Asenjo process from a Kerr-Newman black hole in perfect fluid dark matter

In this work, we provide a thorough analysis of energy extraction via magnetic reconnection, a novel mechanism recently proposed by Comisso and Asenjo, for a Kerr-Newman black hole immersed in a perfect fluid dark matter (PFDM) background. Our studies focus on the impact of black hole spin $a$, electric charge $Q$ and PFDM parameter $\lambda$ on the horizons, ecoregions and circular geodesics at the equatorial plane of this black hole, and how they further influence the reconnection efficiency and energy extraction rate. Our results show that the size of ergoregion does not vary monotonically with increasing dark matter parameters $\lambda$, but it can significantly increase at faster spins ($a>0.8$) as the dark matter parameter $\lambda$ decreases, given the electric charge stays within $Q\in [0.2,0.5]$. We identify the optimal conditions for the combination of $a$, $Q$ and $\lambda$ that enable efficient energy extraction even when the black hole is not rapidly spinning. The Kerr-Newman black hole in PFDM allows for achieving high energy extraction rates comparable to those of most previously studied rotating black holes, which typically require near-extremal spin to reach similar efficiency levels.

[100] 2407.15486

Average speed of sound in neutron stars

The structure of the dense-matter equation of state is essential for the phenomenology of neutron stars. In this work, we relate the thermodynamic properties to the average speed of sound in the interior of a star. We study the consequences of the restoration of conformal symmetry. In particular, we show that if the trace anomaly vanishes in the centers of maximally massive neutron stars, the speed of sound likely exceeds its conformal value and exhibits nonmonotonic behavior. We also find that the additional assumption of positive definiteness of the trace anomaly naturally induces a local peak of the speed of sound at densities realized in the cores of neutron stars. We also discuss the stability condition for the hybrid neutron stars Possible implications for the dense matter equation of state and the phenomenology of neutron stars are also discussed.

[101] 2407.15565

Observational constraints on FLRW, Bianchi type I and V brane models

This study explores the compatibility of Covariant Extrinsic Gravity (CEG) with current cosmological observations. We employ the chi-square statistic and Markov Chain Monte Carlo (MCMC) methods to fit the FLRW and Bianchi type-I and V brane models to the latest datasets, including Hubble, Pantheon+ Supernova samples, Big Bang Nucleosynthesis (BBN), Baryon Acoustic Oscillations (BAO), and the structure growth rate, $f\sigma_8(z)$. Parameters for FLRW universe consist $\left(\Omega^{\text{(b)}}_0, \Omega^{\text{(cd)}}_0, \Omega^{\text{(k)}}_0, H_0, \gamma, \sigma_8\right)$, while for the Bianchi model are $\left(\Omega^{\text{(b)}}_0, \Omega^{\text{(cd)}}_0, \Omega^{{(\beta)}}_0, H_0, \gamma, \Omega^{(\theta)}_0, \sigma_8\right)$. We determine the best values for cosmological parameters. For the FLRW model, these values depend on the sign of $\gamma$: $\gamma > 0$ yields $\gamma =0.00008^{+0.00015}_{-0.00011}$, and $\Omega^{\text{(k)}}_0=0.014^{+0.024}_{-0.022}$ and $\gamma < 0$ leads to $\gamma =-0.0226^{+0.0054}_{-0.0062}$, and $\Omega^{\text{(k)}}_0=0.023^{+0.039}_{-0.041}$. In both cases $\Omega^{\text{(k)}}_0>0$ represents a closed universe. Similarly, for the Bianchi type-V brane model, the parameter values vary with the sign of $\gamma$, resulting in $\gamma = 0.00084^{+0.00019}_{-0.00021}$, $\Omega^{(\beta)}_0 =0.0258^{+0.0052}_{-0.0063} $, and $\Omega^{\theta}_0(\times 10^{-5} ) = 4.19^{+0.67}_{-0.75}$ (as with the density parameter of stiff matter) for $\gamma > 0$, and $\gamma = -0.00107^{+0.00019}_{-0.00020}$, $\Omega^{(\beta)}_0 = 0.0259^{+0.0050}_{-0.0062} $, and $\Omega^{\theta}_0(\times 10^{-5} ) = 4.17^{+0.91}_{-0.98}$ for $\gamma < 0$. In both cases $\Omega^{(\beta)}_0>0$, which represents the Bianchi type-V, because in the Bianchi type-I, $\beta=0$. Utilizing these obtained best values, we analyze the behavior of key cosmological parameters.

[102] 2407.15703

Estimating Probability Densities with Transformer and Denoising Diffusion

Transformers are often the go-to architecture to build foundation models that ingest a large amount of training data. But these models do not estimate the probability density distribution when trained on regression problems, yet obtaining full probabilistic outputs is crucial to many fields of science, where the probability distribution of the answer can be non-Gaussian and multimodal. In this work, we demonstrate that training a probabilistic model using a denoising diffusion head on top of the Transformer provides reasonable probability density estimation even for high-dimensional inputs. The combined Transformer+Denoising Diffusion model allows conditioning the output probability density on arbitrary combinations of inputs and it is thus a highly flexible density function emulator of all possible input/output combinations. We illustrate our Transformer+Denoising Diffusion model by training it on a large dataset of astronomical observations and measured labels of stars within our Galaxy and we apply it to a variety of inference tasks to show that the model can infer labels accurately with reasonable distributions.

[103] 2407.15730

Neural-based Video Compression on Solar Dynamics Observatory Images

NASA's Solar Dynamics Observatory (SDO) mission collects extensive data to monitor the Sun's daily activity. In the realm of space mission design, data compression plays a crucial role in addressing the challenges posed by limited telemetry rates. The primary objective of data compression is to facilitate efficient data management and transmission to work within the constrained bandwidth, thereby ensuring that essential information is captured while optimizing the utilization of available resources. This paper introduces a neural video compression technique that achieves a high compression ratio for the SDO's image data collection. The proposed approach focuses on leveraging both temporal and spatial redundancies in the data, leading to a more efficient compression. In this work, we introduce an architecture based on the Transformer model, which is specifically designed to capture both local and global information from input images in an effective and efficient manner. Additionally, our network is equipped with an entropy model that can accurately model the probability distribution of the latent representations and improves the speed of the entropy decoding step. The entropy model leverages a channel-dependent approach and utilizes checkerboard-shaped local and global spatial contexts. By combining the Transformer-based video compression network with our entropy model, the proposed compression algorithm demonstrates superior performance over traditional video codecs like H.264 and H.265, as confirmed by our experimental results.

[104] 2407.15753

Inference on neutron star parameters and the nuclear equation of state with RIFT, using prior EOS information

In this paper, we present an inference method for determining neutron star parameters and constraining the nuclear equation of state (EOS) using the RIFT parameter inference engine. We incorporate externally-produced prior information about the EOS to improve the accuracy and efficiency of the inference process. We apply this method to the GW170817 event and assess its performance. Our results demonstrate the effectiveness of incorporating prior EOS information in the inference process, leading to sharper conclusions and more rapid inference on new detections. This approach has the potential to enhance our understanding of neutron stars and the nuclear EOS in future gravitational wave observations.

[105] 2407.15804

Coupled phantom cosmological model motivated by the warm inflationary paradigm

In this article, we investigate a coupled phantom dark-energy cosmological model in which the coupling term between a phantom scalar field with an exponential potential and a pressureless dark-matter fluid is motivated by the warm inflationary paradigm. Using methods of qualitative analysis of dynamical systems, complemented by numerical solutions of the evolution equations, we study the late-time behavior of our model. We show that contrary to the uncoupled scenario, the coupled phantom model admits accelerated scaling solutions. However, they do not correspond to a final state of the universe's evolution and, therefore, cannot be used to solve the cosmological coincidence problem. Furthermore, we show that, for certain coupling parameter values, the total equation-of-state parameter's asymptotic behavior is significantly changed when compared to the uncoupled scenario, allowing for solutions less phantom even for steeper potentials of the phantom scalar field.