Gravitational waves can provide crucial insights about the environments in which black holes live. In this work, we use numerical relativity simulations to study the behavior of self-interacting scalar (wavelike) dark matter clouds accreting onto isolated and binary black holes. We find that repulsive self-interactions smoothen the “spike” of an isolated black hole and saturate the density. Attractive self-interactions enhance the growth and result in more cuspy profiles, but can become unstable and undergo explosions akin to the superradiant bosenova that reduce the local cloud density. We quantify the impact of self-interactions on an equal-mass black hole merger by computing the dephasing of the gravitational-wave signal for a range of couplings. We find that repulsive self-interactions saturate the density of the cloud, thereby reducing the dephasing. For attractive self-interactions, the dephasing may be larger, but if these interactions dominate prior to the merger, the dark matter can undergo bosenova during the inspiral phase, disrupting the cloud and subsequently reducing the dephasing.

Gravitational waves emitted by a ringing black hole allow us to perform precision tests of general relativity in the strong field regime. With improvements to our current gravitational wave detectors and upcoming next-generation detectors, developing likelihood-free parameter inference infrastructure is critical as we will face complications like nonstandard noise properties, partial data, and incomplete signal modeling that may not allow for an analytically tractable likelihood function. In this work, we present a proof-of-concept strategy to perform likelihood-free Bayesian inference on ringdown gravitational waves using simulation based inference. Specifically, our method is based on truncated sequential neural posterior estimation, which trains a neural density estimator of the posterior for a specific observed data segment. We setup the ringdown parameter estimation directly in the time domain. We show that the parameter estimation results obtained using our trained networks are in agreement with well-established Markov-chain methods for simulated injections as well as analysis on real detector data corresponding to GW150914. Additionally, to assess our approach’s internal consistency, we show that the density estimators pass a Bayesian coverage test.

Double white dwarfs are important gravitational wave sources for LISA, as they are some of the most numerous compact systems in our Universe. Here, we consider finite-sized effects due to tidal interactions, as they are expected to have a measurable impact on these systems. Previous studies suggested that tidal effects would allow the individual masses to be measured, but there was a subtle error in those analyses. Using a fully Bayesian analysis, we find that while tidal effects do not allow us to constrain the individual masses, they do yield informative lower bounds on the total mass of the system. Including tidal effects is crucial to the accuracy of our estimation of the chirp and total mass. Neglecting tidal effects leads to significant biases toward higher chirp masses, and we see that the lower bound of the total masses is biased toward a higher value as well. For many systems observed by LISA, tidal effects can lead to a “stealth” bias, since only the first derivative of the frequency can be measured. To separate tidal effects from the usual point-particle decay we need to be able to measure the change in the second derivative of the frequency cause by the tides. This can only be done for high frequency systems observed with high signal-to-noise ratio. The bias, if not accounted for, can have significant astrophysical implications; for example, it could lead to an incorrect estimation of the population of potential Type Ia supernovae progenitors.

We present an analytic frequency-domain gravitational waveform model for an inspiraling binary whose center-of-mass undergoes a small acceleration, assumed to be constant during the detection, such as when it orbits a distant tertiary mass. The center-of-mass acceleration along the line of sight is incorporated as a new parameter that perturbs the standard TaylorF2 model. We calculate the wave phase to third post-Newtonian order and first order in the acceleration, including the effects of aligned component spins. It is shown that acceleration most significantly modifies the wave phase in the low frequency portion of the signal, so ground-based detectors with a good sensitivity at low frequencies are the most effective at detecting this effect. We present a Fisher information calculation to quantify detectability at Advanced LIGO A+, Cosmic Explorer, and Einstein Telescope over the mass range of neutron stars and stellar-mass black holes, and discuss degeneracy between acceleration and other parameters. We also determine the parameter space where the acceleration is large enough that the wave phase model would have to be extended to nonlinear orders in the acceleration.

Fixed point lattice actions are designed to have continuum classical properties unaffected by discretization effects and reduced lattice artifacts at the quantum level. They provide a possible way to extract continuum physics with coarser lattices, thereby allowing one to circumvent problems with critical slowing down and topological freezing toward the continuum limit. A crucial ingredient for practical applications is to find an accurate and compact parametrization of a fixed point action, since many of its properties are only implicitly defined. Here we use machine learning methods to revisit the question of how to parametrize fixed point actions. In particular, we obtain a fixed point action for four-dimensional SU(3) gauge theory using convolutional neural networks with exact gauge invariance. The large operator space allows us to find superior parametrizations compared to previous studies, a necessary first step for future Monte Carlo simulations and scaling studies.

Within the framework of the quark delocalization color screening model, a systematic investigation of the anticharmed-strange pentaquark system is performed using the resonance group method. The currently estimations predict three bound states with estimated masses to be 2886 MeV, 3039 MeV, and 3153 MeV, respectively. Additionally, three resonance states are identified in various scattering phase shifts processes. Among them, two resonance states $\mathrm{\Sigma }\overline{D}$ and ${\mathrm{\Sigma }}^{*}{\overline{D}}^{*}$ with quantum number $\frac{1}{2}({\frac{1}{2}}^{-})$ are detected in channels $N{\overline{D}}_s^{*}$ and $N\overline{D}$, and $\mathrm{\Sigma }{\overline{D}}^{*}$ and $\mathrm{\Lambda }\overline{D}$, with masses and decay widths of ($M_R=3053–3055\mathrm{MeV}$, $T_{\text{total}}=13.0–13.4\mathrm{MeV}$) and ($M_R=3389–3390\mathrm{MeV}$, $T_{\text{total}}=10.4\mathrm{MeV}$), respectively. In the $\mathrm{\Lambda }{\overline{D}}^{*}$ and $\mathrm{\Sigma }{\overline{D}}^{*}$ channels, a resonance state with quantum number $\frac{1}{2}({\frac{3}{2}}^{-})$ is discovered, with its mass and decay width being 3250–3252 MeV and 4.4,MeV, respectively. These predicted pentaquark states have $\overline{c}snnn$ quark compositions, allowing them to be recognized as genuine pentaquark states. To validate these predictions, it is expected that upcoming experiments will further explore the predicted resonance and bound states in these possible decay channels.

The cross section for the $e^{+}{e}^{-}\to K_S{K}_L$ process is measured in the center-of-mass energy range from 1000 to 1100 MeV in the experiment with the SND detector at the VEPP-$2000e^{+}{e}^{-}$ collider. The measurement is carried out in the $K_S\to 2{\pi }^0$ decay mode. Data with an integrated luminosity of $20{\mathrm{pb}}^{-1}$ recorded in 2018 at 18 energy points are used in the analysis. The systematic uncertainty in the measured cross section at the maximum of the $\varphi$ resonance is 0.9%. The mass, width of the $\varphi$ meson, and the product of the branching fractions $B(\varphi \to K_S{K}_L)B(\varphi \to e^{+}{e}^{-})$ are determined from the fit to the cross section energy dependence.

In this Letter, we investigate the universal classifications of black hole states by considering them as topological defects within the thermodynamic parameter space. Through the asymptotic behaviors of the constructed vector, our results indicate the existence of four distinct topological classifications, denoted as $W^{1-}$, $W^{0+}$, $W^{0-}$, and $W^{1+}$. Within these classifications, the innermost small black hole states are characterized as unstable, stable, unstable, and stable, respectively, while the outermost large ones exhibit an unstable, unstable, stable, and stable behavior. These classifications also display contrasting thermodynamic properties in both low and high Hawking temperature limits. Furthermore, we establish a systematic ordering of the local thermodynamically stable and unstable black hole states as the horizon radius increases for a specific topological classification. These results reveal the universal topological classifications governing black hole thermodynamics, providing valuable insights into the fundamental nature of quantum gravity.

In this paper, we analyze the pole-skipping phenomena of finite temperature Yang-Mills theory with quark flavors, which is dual to D3-D7 brane systems in bulk. We also consider the external electric field in the boundary field theory, which is dual to the world volume electric field on the D7 brane. We will work in the probe limit where the D7 branes do not backreact to the D3 brane background. In this scenario, we decode the characteristic parameters of the chaos, namely, Lyapunov exponent ${\lambda }_L$ and butterfly velocity $v_b$ from the pole-skipping points by performing the near effective horizon analysis of the linearized Einstein equations. Unlike pure Yang-Mills, once charged quarks with a background electric field are added into the system, the characteristic parameters of the chaos show nontrivial dependence on the quark mass and external electric field. We have observed that ${\lambda }_L$ and $v_b$ decreases with increasing electric field. We further perform the pole-skipping analysis for the gauge invariant sound, shear, and tensor modes of the perturbation in the bulk and discuss their physical importance in the holographic context.

Black hole complementarity posits that the interior of a black hole is not independent from its Hawking radiation. This leads to an apparent violation of causality: the interior can be acausally affected by operators acting solely on the radiation. We argue that this perspective is misleading and that the black hole interior must be viewed as existing in the causal past of the Hawking radiation, despite the fact that they are spacelike separated in the semiclassical description. Consequently, no operation on the Hawking radiation—no matter how complex—can affect the experience of an infalling observer. The black hole interior and the radiation only appear spacelike separated in the semiclassical description because an infalling observer’s ability to access complex information is limited; the chaotic dynamics on the horizon, as viewed from the exterior, then converts any effect caused by such an observer to information in the Hawking radiation which cannot be accessed at the semiclassical level. We arrive at the picture described above by considering a unitary exterior description in which the flow of information is strictly causal, which we extend to apply throughout the entire history of black hole evolution, including its formation. This description uses the stretched event horizon as an inner edge of spacetime, on which the information inside is holographically encoded. We argue that the global spacetime picture arises from coarse graining over black hole microstates, and discuss its relationship with the exterior description.

We argue that algebraic and combinatorial polytope mutations of Fano 3-folds can be identified with mass deformations of associated $2d$ (0,2) supersymmetric gauge theories realized by brane brick models. These are type IIA brane configurations that realize a large family of $2d$ worldvolume theories on probe D1-branes at toric Calabi-Yau 4-folds. We show that brane brick models that are related by mass deformations associated to algebraic and combinatorial polytope mutations of Fano 3-folds have mesonic moduli spaces with the same number of generators. We show that mesonic flavor charges of these generators form convex reflexive lattice polytopes that are dual to the toric diagrams of the Fano 3-folds. The generating function of mesonic gauge invariant operators, also known as the Hilbert series of the mesonic moduli space, appears to be identical for such brane brick models under a particular refinement originating from the $U(1{)}_R$ charges in the brane brick model following the mass deformation.

We explore the physics of relativistic gapless phases defined by a mixed anomaly between two generalized conserved currents. The gapless modes can be understood as Goldstone modes arising from the nonlinear realization of (generically higher-form) symmetries arising from these currents. In some cases, the anomaly cannot be reproduced by any local and unitary theory, indicating that the corresponding symmetries are impossible, in the sense that they cannot appear in a Lorentzian physical system. We give a general construction and illustrate it with several examples. Most notably, we study conformal gravity from this perspective, describing the higher-form symmetries of the linear theory and showing how it can be understood in terms of anomalies. Along the way we clarify some aspects of electric-magnetic duality in linear conformal gravity.

Investigations into Hawking radiation often assume a black hole model featuring an event horizon, despite the growing consensus that such causal structures may not exist in nature. While this assumption is not crucial for deriving the local properties of radiation at future null infinity, it plays a significant role in discussions about Hawking partners—the field modes that purify Hawking radiation. This article aims to explore the definition and fate of Hawking partners in black hole scenarios where semiclassical mass loss due to Hawking radiation is considered. Our analysis avoids the assumption of event horizons and instead focuses on collapse processes that feature a trapped region bounded by a dynamical horizon. We derive the form of the partners, accounting for the effects of backscattering. Furthermore, using these results and mild assumptions, we find that Hawking partners cannot “leak” out of the dynamical horizon to partially purify the Hawking radiation in the regime where general relativity coexists semiclassically with quantum field theory. This finding emphasizes the necessity for new physics, such as quantum gravity, to resolve the final fate of information.

Upper limits and confidence intervals are a convenient way to present experimental results. With modern experiments producing more and more data, it is often necessary to reduce the volume of the results for convenient distribution. A common approach is to take a maximum over a set of upper limits, which yields an upper limit valid for the entire set. This, however, can result in significant sensitivity loss, because we discard more constraining data. In this paper, we introduce functional upper limits and confidence intervals that allow one to summarize results with a small relaxation of constraints. A toy example and an application to upper limits in all-sky continuous gravitational wave searches are worked out.

Gravitational waves (GW) from chirping binary black holes (BBHs) provide unique opportunities to test general relativity (GR) in the strong-field regime. However, testing GR can be challenging when incomplete physical modeling of the expected signal gives rise to systematic biases. In this study, we investigate the potential influence of wave-optics effects in gravitational lensing (which we refer to as microlensing) on tests of GR using GWs for the first time. We utilize an isolated point-lens model for microlensing with the lens mass ranging from $10-{10}^5{M}_{\odot }$ and base our conclusions on an astrophysically motivated population of BBHs in the LIGO-Virgo detector network. Our analysis centers on two theory-agnostic tests of gravity: the inspiral-merger-ringdown consistency test and the parametrized tests, providing insights into deviations from GR across different evolutionary phases of GW signals: inspiral, intermediate, and merger-ringdown. Our findings reveal two key insights: First, microlensing can significantly bias GR tests, with a confidence level exceeding $5\sigma$. Notably, substantial deviations from GR ($\sigma >3$) tend to align with a strong preference for microlensing over an unlensed signal, underscoring the need for microlensing analysis before claiming any erroneous GR deviations. Nonetheless, we do encounter scenarios where deviations from GR remain significant ($1<\sigma <3$), yet the Bayes factor lacks the strength to confidently assert microlensing. Second, deviations from GR correlate with pronounced diffraction effects, which appear when the GW frequency ($f_{\mathrm{GW}}$) aligns with the inverse time delay between microlens-induced images ($t_{\mathrm{d}}$). These false deviations peak in the wave-optics dominated region and fade where $f_{\mathrm{GW}}·t_{\mathrm{d}}$ significantly deviates from unity. Particularly, in the geometrical optics regime $(f_{\mathrm{GW}}·t_{\mathrm{d}}\gg 1)$, biases remain minimal despite instances of strong microlensing effects. Our findings apply broadly to any microlensing scenario, extending beyond specific models and parameter spaces, as we relate the observed biases to the fundamental characteristics of lensing.

We discuss the formation of scalar clouds on charged, spherically symmetric and static stars and black holes. We first discuss Reissner-Nordström black holes with electric and magnetic charge and present new results demonstrating the existence of a second branch of solutions. Moreover, we find that the presence of the magnetic charge allows for a smaller mass and Noether charge when the clouds are close to their minimal possible mean radius. When replacing standard electrodynamics with Born-Infeld (BI) electrodynamics, the background model possesses globally regular, starlike solutions as well as black hole solutions. We show that the former can be scalarized as well, and that the scalar clouds become more compact when decreasing the electric charge of the BI star. Finally, we discuss a magnetic dipole field in the background of the scalarized BI star and show that the strong gravitational field of this star leads to a significant change.

Expanding the work of Wall [Int. J. Mod. Phys. D 24, 1544014 (2015)], we show that black holes obey a second law for linear perturbations to bifurcate Killing horizons, in any covariant higher curvature gravity coupled to scalar and vector fields. The vector fields do not need to be gauged, and (like the scalars) can have arbitrary nonminimal couplings to the metric. The increasing entropy has a natural expression in covariant phase space language, which makes it manifestly invariant under Jacobson-Kang-Myers ambiguities. An explicit entropy formula is given for $f(\text{Riemann})$ gravity coupled to vectors, where at most one derivative acts on each vector. Besides the previously known curvature terms, there are three extra terms involving differentiating the Lagrangian by the symmetric vector derivative (which therefore vanish for gauge fields).

In this paper, we theoretically investigate the deflection of light produced by a topologically charged holonomy corrected Schwarzschild black hole. The study is carried out both in the weak field limit and in the strong field limit. We analytically deduced the expansions for light deflection in the two limits and, from them, we determined the observables in order to provide elements so that observational tools are able to identify these solutions. We model possible gravitational scenarios in order to verify the possible gravitational characteristics of the solution.

Gravitational waves (GWs) passing through a viscous shell of matter are expected to be damped resulting in an increase in the temperature of the fluid as energy is transferred to it from the GWs. In previous work, we constructed a model for this process, obtaining an expression for the temperature distribution inside the shell, and it was shown that the temperature increase can be astrophysically significant. In this paper, we extend the analysis to GW heating and damping following a binary neutron star merge, GW heating during a core-collapse supernova, and primordial gravitational waves due to electroweak first order phase transitions. We model only the GW damping and heating effects, assuming small perturbations on a Minkowski background; thus, we do not obtain precise quantitative predictions, but rather identify scenarios in which the effects may be important.

We demonstrate that a fully metallic and air-filled geodesic waveguide can be employed as an analog electromagnetic model of a static and spherically symmetric gravitational field. By following the Plebanski formalism, a space-time metric of the aforementioned type is first encoded into the electromagnetic properties of a flat space-time region in the form of an isotropic and radially varying refractive index distribution. Then, a three-dimensional, air-filled, and axially symmetric waveguide, composed of two equally spaced and curved metallic surfaces, is employed. Its shape is tailored such that the effective paths, followed by transverse electromagnetic beams of microwave radiation within this waveguide, result equivalent to null-geodesics taking place in the aforementioned refractive medium. This strategy avoids the need for a refractive medium, although it only allows to reproduce the space-time metric on the invariant plane. Two analog electromagnetic models of gravity, using the proposed approach, are designed to reproduce the metric of both a Schwarzschild black hole and a Morris-Thorne wormhole. The results from full-wave simulations demonstrate that a one-dimensional Gaussian beam faithfully follows a path completely equivalent to general relativistic null geodesics with a mean relative error within 4%.