In this paper, we have investigated the role of $H_0$ priors in describing $H_0$ tension and late-time cosmic behavior of the Universe in the framework of $f(T, \mathcal{T})$ gravity. The specific functional form of $f(T, \mathcal{T})$, where $T$ and $\mathcal{T}$ respectively denote the torsion scalar and trace of the energy-momentum tensor, has the potential to show the $H_0$ tension and late-time accelerating behavior. The model parameter space has been obtained using multiple cosmological data sets such as cosmic chronometers (CC), Supernovae Type Ia $PAN^+\&SH0ES$, and baryon acoustic oscillations (BAOs). Also, we have incorporated the $H_0$ priors from the Tip of the Red Giant Branch (TRGB) and HW. The analysis shows the ability of the model to replicate comparative performance with the standard $\Lambda$CDM model through AIC and BIC. From the results obtained, it has been observed that the inclusion of the BAO data set shifts the $H_0$ values lower as compared to that of the $CC+PAN^+\&SH0ES$ data set, whereas the combination of HW prior favors higher $H_0$ values. This demonstrates the sensitivity of the model to different $H_0$ priors. The findings indicate that the $f(T, \mathcal{T})$ gravity model can provide an alternative approach to show cosmological tension and late-time cosmic phenomena.

We simulate high-energy scattering of equal-mass, nonspinning black holes endowed with like charges in full general relativity while varying the impact parameter $b$. We show that electrodynamics does not suppress zoom-whirl orbits for at least charge-to-mass ratios $\lambda = 0.1, 0.4, 0.6$. However, we find that as $\lambda$ increases, the immediate merger and scattering thresholds defining the zoom-whirl regime move to smaller impact parameter $b/M_{\rm ADM}$, with $M_{\rm ADM}$ designating the binary black hole gravitational mass. This demonstrates that charge leaves observable imprints in key properties at energy scales where charge has negligible influence in head-on collisions. Additionally, we find that these threshold impact parameters become universal, i.e., charge-independent, when we normalize $b$ by the sum of the initial BH irreducible masses in the binary ($b/M_{\rm irr}$). This is the first explicit demonstration that the irreducible mass, which is proportional to the black hole areal radius, defines a fundamental gauge-invariant length scale governing horizon scale scattering events in the strong-field, dynamical spacetime regime.

The Hayward regular BH solution attempted to resolve the curvature singularity issue by entering the domain of non-singular spacetimes. Recently, Dutta Roy and Kar (Phys. Rev. D 106, 044028) expanded this solution to encompass a broader range of spacetimes. These spacetimes are constructed based on the Damour-Solodukhin prescription, which involves introducing different metric parameters in the $g_{tt}$ and $g_{rr}$ components of the original Hayward line element, and are characterized by two parameters ($\sigma, \kappa$). This generalization gives rise to both known and novel regular/singular BHs as well as various types of wormhole spacetimes. In this work, we explore the spacetimes that emerge for different values of ($\sigma, \kappa$) from the generalized Hayward metric, particularly focusing on their shadows in vacuum and when surrounded by plasma. Intriguingly, we observe the presence of both photon and anti-photon spheres for certain regular spacetimes. Our study highlights the differences in the shadows of different types of regular spacetime compared to those of the singular BH derived from the generalized Hayward metric and also sheds light on the impact of plasma on the shadow radius.

The detection and subsequent inference of binary black hole signals rely heavily on the accuracy of the waveform model employed. In the highly non-linear, dynamic, and strong-field regime near merger, these waveforms can only be accurately modeled through numerical relativity simulations. Considering the precision requirements of next-generation gravitational wave observatories, we present in this paper high-resolution simulations of four non-spinning quasi-circular binary black hole systems with mass ratios of 1, 2, 3, and 4, conducted using the GR-Athena++ code. We extract waveforms from these simulations using both finite radius and Cauchy characteristic extraction methods. Additionally, we provide a comprehensive error analysis to evaluate the accuracy and convergence of the waveforms. This dataset encompasses gravitational waves of the precision (self-mismatch) demanded by upcoming gravitational detectors such as LISA, Cosmic Explorer, and Einstein Telescope. The waveforms are publicly available on ScholarSphere, and represent the first set of waveforms of the new GR-Athena++ catalog.

Motivated by known facts about effective field theory and non-Abelian gauge theory, we argue that the post-Newtonian approximation might fail even in the limit of weak fields and small velocities under certain conditions. Namely, the post-Newtonian approximation might break down for wide extended bodies with angular momentum, where angular momentum spans significant spacetime curvature. We construct a novel dimensionless quantity that samples this breakdown, and we evaluate it by means of existing analytical solutions of rotating extended bodies and observational data. We give estimates for galaxies and binary systems, as well as our home in the Cosmos, Laniakea. We thus propose that a novel effective field theory of general relativity is needed to account for the onset of nonlocal angular momentum effetcs, with significant consequences for gravitational physics and cosmology at large.

The anomalous velocity deviation in the osculating planetary flyby attracts enough attention as a problem of General Relativity. In connection of rotating weak field massive source the Lense Thirring metric is diagonalized to find the equation of motion from action invariance Hamilton principle in pure relativistic theory. The computation for near Earth flyby shows energy anomaly over the asymptotic in and out velocity obeying Anderson's empirical formula.

In this work, we investigate the existence of wormholes within the framework of Loop Quantum Cosmology, considering isotropic dark matter as the matter source. We examine three distinct density profiles and employ modified field equations along with stress-energy tensor conservation, applying suitable boundary conditions to derive traversable wormhole solutions. We confirm that each obtained solution meets the geometric requirements for wormholes and assess the regularity of these spacetimes by computing the Kretschmann scalar to ensure the absence of singularities. Through the stress-energy tensor, we analyze the conditions under which energy conditions may be violated in this model. We explore the geometry of these wormholes using embedding diagrams, and evaluate the stability of the solutions by examining the speed of sound. Lastly, we compute the amount of exotic matter necessary to sustain these structures using the Volume Integral Quantifier.

We investigate the observational implications of a gravitational model wherein the gravitational constant $G$ and the cosmological constant $\Lambda$ exhibit scale-dependent behavior at the perturbative level, while preserving the General Relativity (GR) field equations at the background. This model is motivated by the potential influence of large-scale (infrared) Renormalization Group (RG) corrections to gravity and is constructed upon an effective action incorporating a scale definition via Lagrange multipliers. We explore the effects of these modifications during the recombination epoch with particular focus on their impact on the structure of acoustic oscillations. Additionally, we perform a comprehensive parameter fitting analysis using data from the Cosmic Microwave background (CMB), type Ia Supernovae (SN Ia), Baryon Acoustic Oscilations (BAO) and Redshift Space Distortions(RSD). Our results indicate that the RG corrections here considered are consistent with the main predictions of the $\Lambda$CDM model, and they slightly increase the uncertainties in the parameter estimations. Such small differences cannot be used to dismiss the current cosmological tensions.

A connection between regular black holes and horizonless ultracompact objects was proposed in~\cite{Carballo-Rubio:2022nuj}. In this paper, we construct a model of a horizonless compact object, specifically an anisotropic gravastar with continuous pressure, that corresponds to regular black hole spacetime in the appropriate limit. The construction begins by modeling an equation of state that satisfies the anisotropic gravastar conditions and transitions to the de Sitter ($p=-\epsilon$) upon horizon formation. The spacetime structure is similar to the {\it Quantum Horizonless Compact Object} (QHCO) described in~\cite{Chen:2024ibc}. Within this model, we also generate images of the corresponding objects surrounded by a thin accretion disk. The resulting images reveal that assuming that the emitting matter exists only outside the object, the inner light ring structure closely resembles that of the horizonless configuration of a regular black hole and the QHCO, yet it exhibits a distinct light ring structure compared to the thin-shell gravastar model. However, the opposite occurs when emitting matter is taken into account inside the object.

The quasinormal mode spectrum of gravitational waves emitted during the black hole ringdown relaxation phase, following the merger of a black hole binary, is a crucial target of gravitational wave astronomy. By considering causality constraints on the on-shell graviton three-point couplings within a weakly coupled gravity theory, we present arguments indicating that the contributions to the physics of linear and quadratic quasinormal modes from higher derivative gravity theories are either negligible or vastly suppressed for Schwarzschild and Kerr black holes. Their spectrum and interactions are dictated solely by Einstein's gravity.

The presence of a massive body between the Earth and a gravitational-wave source will produce the so-called gravitational lensing effect. In the case of strong lensing, it leads to the observation of multiple deformed copies of the initial wave. Machine-learning (ML) models have been proposed for identifying these copies much faster than optimal Bayesian methods, as will be needed with the detection rate of next-generation detector. Most of these ML models are based on a time-frequency representation of the data that discards the phase information. We introduce a neural network that directly uses the time series data to retain the phase, limit the pre-processing time and keep a one-dimensional input. We show that our model is more efficient than the base model used on time-frequency maps at any False Alarm Rate (FPR), up to $\sim 5$ times more for an FPR of $10^{-4}$. We also show that it is not significantly impacted by the choice of waveform model, by lensing-induced phase shifts and by reasonable errors on the merger time that induce a misalignment of the waves in the input.

In this work, we elaborate further on a 4D cosmological Running-Vacuum-type Model (RVM) of inflation that characterises string-inspired Chern-Simons (CS) gravity. It has been shown that inflation in such models is caused by a condensation of the gravitational CS (gCS) terms induced by primordial gravitational waves (GW), which leads to a linear-axion potential, thus breaking the shift symmetry, and lifting its periodicity (monodromy). We demonstrate here that this inflationary phase may be metastable, due to the existence of non-trivial imaginary parts of the gCS condensate. These imaginary parts are quantum effects, proportional to appropriate commutators of GW perturbations. As we stress, their existence is quantum-ordering-scheme dependent. We argue here in favor of a physical importance of such imaginary parts, which we compute to second order in the GW (tensor) perturbations in the framework of a specific gauge-fixed effective Lagrangian, within a (mean field) weak-quantum-gravity path integral approach. We pay specific attention to the various space-time boundary terms. We thus provide an estimate of the life time of inflation. On matching our results with the relevant inflationary phenomenology, we fix the quantum-ordering ambiguities, and obtain an order-of-magnitude constraint on the ratio of the string energy scale $M_s$ in this model to the (four-spacetime-dimensional) reduced Planck mass $M_{\rm Pl}$, specifically, $M_s/M_{\rm Pl} = \mathcal{O}(10^{-1})$. This is consistent with the corresponding estimate obtained in previous analyses by the authors in this framework, based on a dynamical-system approach to linear-axion RVM inflation. Finally, we examine the role of periodic modulations in the axion potential induced by non-perturbative stringy effects on the slow-roll inflationary parameters, and find compatibility with the cosmological data.

We investigate the properties of anisotropic white dwarf stars within the rainbow gravity adopting for matter content the Chandrasekhar model based on an ideal Fermi gas at zero temperature. We study in detail the effects of the anisotropic factor on stellar mass and radius, the speed of sound, and the relativistic adiabatic index in both radial and tangential directions. We find that causality is never violated, whereas the stability criterion based on the relativistic adiabatic index is not met when the objects are characterized by a positive anisotropic factor close to the Chandrasekhar limit. We present this significant observation here for the first time, to the best of our knowledge.

Using the AdS/CFT correspondence, this paper investigates the holographic images of a charged black hole within the context of Lorentz symmetry breaking massive gravity. The photon rings, luminosity-deformed rings, or light points from various observational perspectives are obtained. We also study the influences of both the chemical potential and temperature on the Einstein ring. Unlike the previous work, which primarily examines the effect of chemical potential on ring radius at high temperatures and find no change in the radius with varying chemical potential, we also investigate the effect of chemical potential on the ring radius at low temperature besides at high temperature. Our findings indicate that at low temperatures, the photon ring radius decreases with increasing of chemical potential, while at high temperatures, the results are consistent with previous studies. Additionally, we explore the impact of the model parameter {\lambda} on the Einstein ring radius and find the the ring radius increases as the model parameter {\lambda} increases. More interestingly, for the large chemical potential, u = 1, the temperature dependence of the photon ring radius is reversed for {\lambda} = 2 and {\lambda} = 4. Conversely, for a small chemical potential u = 0.1, the temperature dependence of the Einstein ring stays the same as {\lambda} = 2 and {\lambda} = 4.

On a class of dynamical spacetimes which are asymptotic as $t\to\infty$ to a stationary spacetime containing a horizon $\mathcal{H}_0$, we show the existence of a unique null hypersurface $\mathcal{H}$ which is asymptotic to $\mathcal{H}_0$. This is a special case of a general unstable manifold theorem for perturbations of flows which translate in time and have a normal sink at an invariant manifold in space. Examples of horizons $\mathcal{H}_0$ to which our result applies include event horizons of subextremal Kerr and Kerr-Newman black holes as well as event and cosmological horizons of subextremal Kerr-Newman-de Sitter black holes. In the Kerr(-Newman) case, we show that $\mathcal{H}$ is equal to the boundary of the black hole region of the dynamical spacetime.

We examine the vacuum state and its corresponding renormalized stress-energy tensor (RSET) in static horizonless regular spacetime in both two- and four-dimensions. Using the local field formulation of the anomaly-induced effective action, we show that the regularities of the spacetime and the RSET dictate the appropriate vacuum state. Furthermore, through a case study under the horizonless Bardeen-type spacetime, we demonstrate that the preferred vacuum state is not the Boulware vacuum, but a non-trivial one with a different RSET profile.

This collection of perspective pieces captures recent advancements and reflections from a dynamic research community dedicated to bridging quantum gravity, hydrodynamics, and emergent cosmology. It explores four key research areas: (a) the interplay between hydrodynamics and cosmology, including analog gravity systems; (b) phase transitions, continuum limits and emergent geometry in quantum gravity; (c) relational perspectives in gravity and quantum gravity; and (d) the emergence of cosmological models rooted in quantum gravity frameworks. Each contribution presents the distinct perspectives of its respective authors. Additionally, the introduction by the editors proposes an integrative view, suggesting how these thematic units could serve as foundational pillars for a novel theoretical cosmology framework termed "hydrodynamics on superspace".

We present a study of shearfree gravitational collapse using cylindrically symmetric spacetimes whose interior is a non-rotating dissipative fluid bounded by a cylindrical hypersurface beyond which is an Einstein-Rosen vacuum exterior. We consider three different pressure configurations: axially, azimuthally, and radially directed, for which we find new exact interior solutions of the field equations. We show that the matching conditions cannot be satisfied by the fluid with radial pressure, while the axial and azimuthal cases with a lapse function depending only on the time coordinate do satisfy these constraints. We derive, for both cases, a sufficient condition for an emission of gravitational radiation from the interior towards the exterior, We therefore show that, at variance with what happens for spherical symmetry, in the simplified picture of an infinite cylinder of anisotropic shearfree matter, gravitational waves can be emitted during collapsing motion.

Making cosmological predictions in a multiverse is a fundamental theoretical challenge. Assuming that (quasi-)de Sitter vacua are quantum mechanically described by a finite-dimensional Hilbert space, we develop a detailed framework for making explicit anthropic predictions. A key challenge which we attempt to overcome arises because, almost unavoidably, cosmologies that asymptote to Minkowski space exist. We then apply our framework to predicting the scale of inflation. We find that, even if eternal inflation is allowed, our predictions depend on creation rates of universes from nothing. These, in turn, are highly sensitive to the existence of end-of-the-world branes. The rates for the creation of universes from nothing are the dominant ingredient for `Swampy Landscapes', which may have no metastable de Sitter vacua but only slow-roll solutions. In `Rocky Landscapes', where long-lived de Sitter vacua are abundant, tunneling rates between such vacua represent a further key factor for deriving predictions.

Spacetime singularities pose a long-standing puzzle in quantum gravity. Unlike Schwarzschild, a generic family of black holes gives rise to a Cauchy horizon on which, even in the Hartle-Hawking state, quantum observables such as $\langle T_{\mu\nu} \rangle$ -- the expectation value of the stress-energy tensor -- can diverge, causing a breakdown of semiclassical gravity. Because they are diagnosed within quantum field theory (QFT) on a smooth background, these singularities may provide a better-controlled version of the spacetime singularity problem, and merit further study. Here, I highlight a mildness puzzle of Cauchy horizon singularities: the $\langle T_{\mu\nu} \rangle$ singularity is significantly milder than expected from symmetry and dimensional analysis. I address the puzzle in a simple spacetime $W_P$, which arises universally near all black hole Cauchy horizons: the past of a codimension-two spacelike plane in flat spacetime. Specifically, I propose an extremely broad QFT construction in which, roughly speaking, Cauchy horizon singularities originate from operator insertions in the causal complement of the spacetime. The construction reproduces well-known outer horizon singularities (e.g., in the Boulware state), and remarkably, when applied to $W_P$, gives rise to a universal mild singularity structure for robust singularities, ones whose leading singular behavior is state-independent. I make non-trivial predictions for all black hole Cauchy horizon singularities using this, and discuss extending the results beyond robust singularities and the strict near Cauchy horizon limit.

Supermassive binary black holes are a key target for the future Laser Interferometer Space Antenna, and excellent multi-messenger sources with gravitational waves. However, unique features of their electromagnetic emission that are needed to distinguish them from single supermassive black holes are still being established. Here, we conduct the first magnetohydrodynamic simulation of accretion onto eccentric binary black holes in full general relativity incorporating synchrotron radiation transport through their dual-jet. We show that the total accretion rate, jet Poynting luminosity, and the optically thin synchrotron emission exhibit periodicity on the binary orbital period, demonstrating explicitly, for the first time, that the binary accretion rate periodicity can be reflected in its electromagnetic signatures. Additionally, we demonstrate that during each periodic cycle eccentric binaries spend more time in a low emission state than in a high state. Furthermore, we find that the gravitational wave bursts from eccentric binaries are coincident with the bursts in their jet luminosity and synchrotron emission. We discuss how multimessenger observations of these systems can probe plasma physics in their jet.

Recent literature on core-collapse supernovae suggests that a black hole (BH) can form within $\sim 1$ s of shock revival, while still culminating in a successful supernova. We refer to these as black hole supernovae, as they are distinct from other BH formation channels in both timescale and impact on the explosion. We simulate these events self-consistently from core-collapse until $20\text{-}50$ days after collapse using three axisymmetric models of a $60$ M$_\odot$ zero-age main sequence progenitor star and investigate how the composition of the ejecta is impacted by the BH formation. We employ Skyrme-type equations of state (EOSs) and vary the uncertain nucleonic effective mass, which affects the pressure inside the proto-neutron star through the thermal part of the EOS. This results in different BH formation times and explosion energies at BH formation, yielding final explosion energies between $0.06\text{-}0.72\times 10^{51}$ erg with $21.8\text{-}23.3$ M$_\odot$ of ejecta, of which $0\text{-}0.018$ M$_\odot$ is $^{56}$Ni. Compared to expectations from 1D simulations, we find a more nuanced EOS dependence of the explosion dynamics, the mass of the BH remnant, and the elemental composition of the ejecta. We investigate why the explosions survive despite the massive overburden and link the shape of the diagnostic energy curve and character of the ejecta evolution to the progenitor structure.

This study investigates the structural properties of strange quark stars (SQS) using a Quantum Chromodynamics (QCD) perturbative model combined with the latest Particle Data Group dataset. Given the energy scale present in compact stars, QCD perturbation theory alone may not fully explain their structure. To account for non-perturbative contributions, we incorporate a density-dependent effective bag parameter, $B$, and derive the equation of state (EOS) for strange quark matter (SQM). We start by demonstrating the limitations of EOSs with a constant $B$ in describing massive objects with $ M_{TOV}> 2M_{\odot} $. Subsequently, we show that considering $B$ as a density-dependent function significantly changes the results. Our definition of $B$ includes two parameters determined by both theoretical and observational constraints. We demonstrate that incorporating a density-dependent $B$ into the perturbative EOS can yield SQSs with masses exceeding $2M_{\odot}$, while complying with gravitational wave constraints such as tidal deformability, and thermodynamic considerations, including stability conditions and speed of sound behavior. Specifically, we show that massive compact objects like PSR J0952-0607, PSR J2215+5135, PSR J0740+6620, and the secondary mass of GW190814 can be SQSs. Additionally, we compare our EOS with the EOS of the authors who use a generalized polytropic form with adjustable parameters and obtain an interesting result.

Nonassociative modifications of general relativity, GR, and quantum gravity, QG, models naturally arise as star product and R-flux deformations considered in string/ M-theory. Such nonassociative and noncommutative geometric and quantum information theories were formulated on phase spaces defined as cotangent Lorentz bundles enabled with nonassociative symmetric and nonsymmetric metrics and nonlinear and linear connection structures. We outline the analytic methods and proofs that corresponding geometric flow evolution and dynamical field equations can be decoupled and integrated in certain general off-diagonal forms. New classes of solutions describing nonassociative black holes, wormholes, and locally anisotropic cosmological configurations are constructed using such methods. We develop the Batalin-Vilkovisky, BV, formalism for quantizing modified gravity theories, MGTs, involving twisted star products and semi-classical models of nonassociative gauge gravity with de Sitter/affine/ Poincar\'{e} double structure groups. Such theories can be projected on Lorentz spacetime manifolds in certain forms equivalent to GR or MGTs with torsion generalizations etc. We study the properties of the classical and quantum BV operators for nonassociative phase spaces and nonassociative gauge gravity. Recent results and methods from algebraic QFT are generalized to involve nonassociative star product deformations of the anomalous master Ward identity. Such constructions are elaborated in a nonassociative BV perspective and for developing non-perturbative methods in QG.

This paper investigates the trajectories of neutral particles in the Schwarzschild-Melvin spacetime. After reduction by cyclic coordinates this problem reduces to investigating a two-degree-of-freedom Hamiltonian system that has no additional integral. A classification of regions of possible motion of a particle is performed according to the values of the momentum and energy integrals. Bifurcations of periodic solutions of the reduced system are analyzed using a Poincare map.

In a recent paper, Anupam, Chowdhury, and Sen [arXiv:2308.00038] constructed the non-extremal saddle that reproduces the supersymmetric index of the BMPV black hole with three independent charges in the classical limit. This saddle solution is a finite temperature complex solution saturating the BPS bound. In this paper, we write this solution in a canonical form in terms of harmonic functions on three-dimensional flat base space, thereby showing that it is supersymmetric. We also show that it exhibits the new form of attraction.

The It\^{o} and Stratonovich approaches are two ways to integrate stochastic differential equations. Detailed knowledge of the origin of the stochastic noise is needed to determine which approach suits a particular problem. I discuss this topic pedagogically in stochastic inflation, where the noise arises from a changing comoving coarse-graining scale or, equivalently, from `zooming in' into inflating space. I introduce a zoom-in scheme where deterministic evolution alternates with instantaneous zoom-in steps. I show that this alternating zoom-in scheme is equivalent to the It\^{o} approach in the Markovian limit, while the Stratonovich approach doesn't have a similar interpretation. In the full non-Markovian setup, the difference vanishes. The framework of zoom-in schemes clarifies the relationship between computations in stochastic inflation, linear perturbation theory, and the classical $\Delta N$ formalism. It informs the numerical implementation of stochastic inflation and is a building block for a first-principles derivation of the stochastic equations.

In the framework of AdS/CFT correspondence, the Fefferman--Graham (FG) gauge offers a useful way to express asymptotically anti-de Sitter spaces, allowing a clear identification of their boundary structure. A known feature of this approach is that choosing a particular conformal representative for the boundary metric breaks explicitly the boundary scaling symmetry. Recent developments have shown that it is possible to generalize the FG gauge to restore boundary Weyl invariance by adopting the Weyl--Fefferman--Graham gauge. In this paper, we focus on three-dimensional gravity and study the emergence of a boundary Weyl structure when considering the most general AdS boundary conditions introduced by Grumiller and Riegler. We extend the holographic renormalization scheme to incorporate Weyl covariant quantities, identifying new subleading divergences appearing at the boundary. To address these, we introduce a new codimension-two counterterm, or corner term, that ensures the finiteness of the gravitational action. From here, we construct the quantum-generating functional, the holographic stress tensor, and compute the corresponding Weyl anomaly, showing that the latter is now expressed in a full Weyl covariant way. Finally, we discuss explicit applications to holographic integrable models and accelerating black holes. For the latter, we show that the new corner term plays a crucial role in the computation of the Euclidean on-shell action.

Gravitational waves from core-collapse supernovae are a promising yet challenging target for detection due to the stochastic and complex nature of these signals. Conventional detection methods for core-collapse supernovae rely on excess energy searches because matched filtering has been hindered by the lack of well-defined waveform templates. However, numerical simulations of core-collapse supernovae have improved our understanding of the gravitational wave signals they emit, which enables us, for the first time, to construct a set of templates that closely resemble predictions from numerical simulations. In this study, we investigate the possibility of detecting gravitational waves from core-collapse supernovae using a matched-filtering methods. We construct a theoretically-informed template bank and use it to recover a core-collapse supernova signal injected into real LIGO-Virgo-KAGRA detector data. We evaluate the detection efficiency of the matched-filtering approach and how well the injected signal is reconstructed. We discuss the false alarm rate of our approach and investigate the main source of false triggers. We recover 88\% of the signals injected at a distance of 1 kpc and 50% of the signals injected at 2 kpc. For more than 50% of the recovered events, the underlying signal characteristics are reconstructed within an error of 15%. We discuss the strengths and limitations of this approach and identify areas for further improvements to advance the potential of matched filtering for supernova gravitational-wave detection. We also present the open-source Python package SynthGrav used to generate the template bank.

We discuss the classical and quantum chaos of closed strings on a recently constructed charged confining holographic background. The confining background corresponds to the charged soliton, which is a solution of minimal $d=5$ gauged supergravity. The solution has a compact spacelike direction with a Wilson line on a circle and asymptotes to $AdS_5$ with a planar boundary. For the classical case, we analyze the chaos using the power spectrum, Poincar\'{e} sections, and Lyapunov exponents, finding that both energy and charge play constructive effects on enhancing the chaotic nature of the system. We similarly analyze quantum chaos using the distribution of the spectrum's level-spacing and out-of-time-ordered correlators and thoroughly investigate the effects of charge and energy. A gradual transition from a chaotic to an integrable regime is obtained as the energy and charge increase from lower to higher values, with charge playing a subdominant role.

We consider 4D $SU(N)$ gauge theories coupled to gravity in the Causal Dynamical Triangulations (CDT) approach, focusing on the topological classification of the gauge path-integral over fixed triangulations. We discretize the topological charge and, after checking the emergence of topology and the continuum scaling on flat triangulations, we show that topology emerges on thermalized triangulations only in the so-called $C$-phase of CDT, thus enforcing the link between such phase and semi-classical space-time. We also provide a tool to visualize the topological structures.