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the nonlinear character of general relativity leaves its imprint in the coalescence of two black holes, from the inspiral to the final ringdown stage. to quantify the impact of nonlinearities, we work at second order in black hole perturbation theory and we study the excitation of second-order modes relative to the first-order modes that drive them as we vary the black hole spin and the initial data for the perturbations. the relative amplitude of second-order modes is only mildly dependent on the initial data that we consider, but it strongly decreases for large black hole spins. this implies that the extrapolation of calculations based on the kerr-cft correspondence to subextremal kerr black holes should be viewed with caution | spin dependence of black hole ringdown nonlinearities |
in this paper, we report on exact charged black hole solutions in symmergent gravity with maxwell field. symmergent gravity induces the gravitational constant g, quadratic curvature coefficient $c_{\mathrm{o}}$ , and the vacuum energy $v_{\mathrm{o}}$ from the flat spacetime matter loops. in the limit in which all fields are degenerate in mass, the vacuum energy $v_{\mathrm{o}}$ can be expressed in terms of g and $c_{\mathrm{o}}$ . we parametrize deviation from this limit by a parameter ${\hat \alpha}$ such that the black hole spacetime is de sitter (ds) for ${\hat \alpha} \lt 1$ and anti-de sitter (ads) for ${\hat \alpha} \gt 1$ . in our analysis, we study horizon formation, shadow cast and gravitational lensing as functions of the black hole charge, and find that there is an upper bound on the charge. at relatively low values of charge, applicable to astronomical black holes, we determine constraints on $c_{\mathrm{o}}$ and ${\hat \alpha}$ using the event horizon telescope (eht) data from sgr. a* and m87*. we apply these constraints to reveal how the shadow radius behaves as the observer distance $r_\mathrm{o}$ varies. it is revealed that black hole charge directly influences the shadow silhouette, but the symmergent parameters have a tenuous effect. we also explored the weak field regime by using the gauss-bonnet theorem to study the weak deflection angle caused by the m87* black hole. we have found that impact parameters comparable to the actual distance d = 16.8 mpc show the potential detectability of such an angle through advanced astronomical telescopes. overall, our results provide new insights into the behavior of charged black holes in the context of symmergent gravity and offer a new way to test these theories against observational data. | constraints on charged symmergent black hole from shadow and lensing |
the black hole weak gravity conjecture (wgc) is a set of linear inequalities on the four-derivative corrections to einstein-maxwell theory. remarkably, in four dimensions, these combinations appear in the 2 → 2 photon amplitudes, leading to the hope that the conjecture might be supported using dispersion relations. however, the presence of a pole arising in the forward limit due to graviton exchange greatly complicates the use of such arguments. in this paper, we apply recently developed numerical techniques to handle the graviton pole, and we find that standard dispersive arguments are not strong enough to imply the black hole wgc. specifically, under a fairly typical set of assumptions, including weak coupling of the eft and regge boundedness, a small violation of the black hole wgc is consistent with unitarity and causality. we quantify the size of this violation, which vanishes in the limit where gravity decouples and also depends logarithmically on an infrared cutoff. we discuss the meaning of these bounds in various scenarios. we also implement a method for bounding amplitudes without manifestly positive spectral densities, which could be applied to any system of non-identical states, and we use it to improve bounds on the eft of pure photons in absence of gravity. | bounding violations of the weak gravity conjecture |
in this paper, we study topological numbers for five-, six- and seven-dimensional anti-de sitter black holes in the ghost-free massive gravity. we find that when the black holes are charged, they have the same topological number. the topological numbers for the uncharged black holes are 0 or 1, and the specific values are determined by the values of the black holes' parameters. since k and c02c2m2 appear together in the generalized free energy in the form of k +c02c2m2 , where k characterizes the horizon curvature and c2m2 is the coefficient of the second term of massive potential associated with the graviton mass, this result is applicable to the black holes with the spherical, ricci flat or hyperbolic horizons. this work shows that the parameters of the ghost-free massive gravity play an important role in topological classes of black holes. | topological classes of higher-dimensional black holes in massive gravity |
it may soon be possible for advanced ligo to detect hundreds of binary black hole mergers per year. we show how the accumulation of many such measurements will allow for the detection of gravitational-wave memory: a permanent displacement of spacetime that comes from strong-field, general relativistic effects. we estimate that advanced ligo operating at design sensitivity may be able to make a signal-to-noise ratio 3 (5) detection of memory with ∼35 (90 ) events with masses and distance similar to gw150914. we highlight the importance of incorporating higher-order gravitational-wave modes for parameter estimation of binary black hole mergers, and describe how our methods can also be used to detect higher-order modes themselves before advanced ligo reaches design sensitivity. | detecting gravitational-wave memory with ligo: implications of gw150914 |
despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. orbital eccentricity is one of the clearest tracers of binary formation channels. identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effects of eccentricity. here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (o3) of the ligo and virgo detectors. we identified no new high-significance candidates beyond those that were already identified with searches focusing on quasi-circular binaries. we determine the sensitivity of our search to high-mass (total mass $m>70$ $m_\odot$) binaries covering eccentricities up to 0.3 at 15 hz orbital frequency, and use this to compare model predictions to search results. assuming all detections are indeed quasi-circular, for our fiducial population model, we place an upper limit for the merger rate density of high-mass binaries with eccentricities $0 < e \leq 0.3$ at $0.33$ gpc$^{-3}$ yr$^{-1}$ at 90\% confidence level. | search for eccentric black hole coalescences during the third observing run of ligo and virgo |
we present a compact formula for the supersymmetric partition function of 2d n=(2,2), 3d n=2 and 4d n=1 gauge theories on $\sigma_g \times t^n$ with partial topological twist on $\sigma_g$, where $\sigma_g$ is a riemann surface of arbitrary genus and $t^n$ is a torus with n=0,1,2, respectively. in 2d we also include certain local operator insertions, and in 3d we include wilson line operator insertions along $s^1$. for genus g=1, the formula computes the witten index. we present a few simple abelian and non-abelian examples, including new tests of non-perturbative dualities. we also show that the large n partition function of abjm theory on $\sigma_g \times s^1$ reproduces the bekenstein-hawking entropy of bps black holes in ads$_4$ whose horizon has $\sigma_g$ topology. | supersymmetric partition functions on riemann surfaces |
using recent results in four-derivative 5d n =2 minimal gauged supergravity, we evaluate the regularized on-shell action of the euclidean solution in this theory that admits a lorentzian continuation to an ads5 black hole with one electric charge and two angular momenta. we focus on the supersymmetric limit of this solution and employ holography to show that the result can be expressed purely in terms of angular momentum fugacities and the 't hooft anomalies for the u (1 )r r symmetry of the dual 4d n =1 superconformal field theory. this holographic calculation is in perfect agreement with recent studies of the 4d n =1 superconformal index "on the second sheet." we illustrate the utility of these results in two classes of 4d n =1 holographic scfts that have 't hooft anomalies with suitable large-n behavior that leads to nontrivial corrections at first subleading order in the 1 /n expansion. we also explicitly calculate the wald entropy of the black hole solution and delineate the leading four-derivative corrections to the bekenstein-hawking entropy. | higher derivative corrections and ads5 black holes |
we propose a doubly holographic version of the semiclassical island formula for the entanglement negativity in the framework of the defect ads/bcft correspondence where the anti-de sitter (ads) bulk contains a defect conformal matter theory. in this context, we propose a defect extremal surface (des) formula for computing the entanglement negativity modified by the contribution from the defect matter theory on the end-of-the-world brane. the equivalence of the des proposal and the semiclassical island formula for the entanglement negativity is demonstrated in ads3/bcft2 framework. furthermore, in the time-dependent ads3/bcft2 scenarios involving eternal black holes in the lower dimensional effective description, we investigate the time evolution of the entanglement negativity through the des and the island formulas and obtain the analogs of the page curves. | defect extremal surfaces for entanglement negativity |
we discuss a 1+1 dimensional generalization of the sachdev-ye-kitaev model. the model contains n majorana fermions at each lattice site with a nearest-neighbour hopping term. the syk random interaction is restricted to low momentum fermions of definite chirality within each lattice site. this gives rise to an ordinary 1+1 field theory above some energy scale and a low energy syk-like behavior. we exhibit a class of low-pass filters which give rise to a rich variety of hyperscaling behaviour in the ir. we also discuss another set of generalizations which describes probing an syk system with an external fermion, together with the new scaling behavior they exhibit in the ir. | higher dimensional generalizations of the syk model |
we compute the length of spacelike geodesics anchored at opposite sides of certain double-sided flow geometries in two dimensions. these geometries are asymptotically anti-de sitter but they admit either a de sitter or a black hole event horizon in the interior. while in the geometries with black hole horizons, the geodesic length always exhibit linear growth at late times, in the flow geometries with de sitter horizons, geodesics with finite length only exist for short times of the order of the inverse temperature and they do not exhibit linear growth. we comment on the implications of these results towards understanding the holographic proposal for quantum complexity and the holographic nature of the de sitter horizon. | holographic complexity and de sitter space |
we have previously constructed a waveform model, $\mathtt{s}\mathtt{e}\mathtt{o}\mathtt{b}\mathtt{n}\mathtt{r}\mathtt{e}$ , for spinning binary black hole (bbh) moving along eccentric orbit based on effective-one-body (eob) formalism. in the current paper, we update $\mathtt{s}\mathtt{e}\mathtt{o}\mathtt{b}\mathtt{n}\mathtt{r}\mathtt{e}$ waveform model in the following three respects. firstly, we update the eob dynamics from $\mathtt{s}\mathtt{e}\mathtt{o}\mathtt{b}\mathtt{n}\mathtt{r}\mathtt{v}\mathtt{1}$ to $\mathtt{s}\mathtt{e}\mathtt{o}\mathtt{b}\mathtt{n}\mathtt{r}\mathtt{v}\mathtt{4}$ . secondly we properly treat the schott term which has been ignored in previous $\mathtt{s}\mathtt{e}\mathtt{o}\mathtt{b}\mathtt{n}\mathtt{r}\mathtt{e}$ . thirdly, we construct a new factorized waveform including (l, |m|) = (2, 2), (2, 1), (3, 3), (4, 4) modes based on eob formalism, which is valid for spinning bbhs in general equatorial orbit. following our previous $\mathtt{s}\mathtt{e}\mathtt{o}\mathtt{b}\mathtt{n}\mathtt{r}\mathtt{e}$ waveform model, we call our new waveform model $\mathtt{s}\mathtt{e}\mathtt{o}\mathtt{b}\mathtt{n}\mathtt{r}\mathtt{e}\mathtt{h}\mathtt{m}$ . the (l, |m|) = (2, 2) mode waveform of $\mathtt{s}\mathtt{e}\mathtt{o}\mathtt{b}\mathtt{n}\mathtt{r}\mathtt{e}\mathtt{h}\mathtt{m}$ can fit the original $\mathtt{s}\mathtt{e}\mathtt{o}\mathtt{b}\mathtt{n}\mathtt{r}\mathtt{v}\mathtt{4}$ waveform very well in the case of a quasi-circular orbit. we have validated $\mathtt{s}\mathtt{e}\mathtt{o}\mathtt{b}\mathtt{n}\mathtt{r}\mathtt{e}\mathtt{h}\mathtt{m}$ waveform model through comparing the waveform against the simulating extreme spacetimes (sxs) catalog. the comparison is done for bbh with total mass in (20, 200)m ⊙ using advanced ligo designed sensitivity. for the quasi-circular cases we have compared our (2, 2) mode waveforms to the 281 numerical relativity (nr) simulations of bbh along quasi-circular orbits. all of the matching factors are bigger than 98%. for the elliptical cases, 24 nr simulations of bbh along an elliptic orbit are used. for each elliptical bbh system, we compare our modeled gravitational polarizations against the nr results for different combinations of the inclination angle, the initial orbit phase and the source localization in the sky. we use the minimal matching factor respect to the inclination angle, the initial orbit phase and the source localization to quantify the performance of the higher modes waveform. we found that after introducing the higher modes, the minimum of the minimal matching factor among the 24 tested elliptical bbhs increases from 90% to 98%. our $\mathtt{s}\mathtt{e}\mathtt{o}\mathtt{b}\mathtt{n}\mathtt{r}\mathtt{e}\mathtt{h}\mathtt{m}$ waveform model can match all tested 305 sxs waveforms better than 98% including highly spinning (χ = 0.99) bbh, highly eccentric (e ≈ 0.6 at reference frequency mf 0 = 0.002) bbh and large mass ratio (q = 10) bbh. | a higher-multipole gravitational waveform model for an eccentric binary black holes based on the effective-one-body-numerical-relativity formalism |
it is broadly believed that quasinormal modes (qnms) cannot tell the black-hole near-horizon geometry, because usually the low-lying modes are determined by the scattering of perturbations around the peak of the effective potential. using the general parametrization of the black-hole spacetimes respecting the generic post-newtonian asymptotic, we will show that tiny modifications of the schwarzschild/kerr geometry in a small region near the event horizon lead to almost the same schwarzschild/kerr fundamental mode, but totally different first few overtones. having in mind that the first several overtones affect the quasinormal (qn) ringing at its early and intermediate stage [m. giesler, m. isi, m. scheel, and s. teukolsky, phys. rev. x 9, 041060 (2019)], we argue that the near-horizon geometry could in principle be studied via the first few overtones of the qn spectrum, which is important because corrections to the einstein theory must modify precisely the near-horizon geometry, keeping the known weak field regime. we discuss the connection of this observation with the so called "overtones' instability" recently studied in [j. jaramillo et. al. phys. rev. lett. 128, 211102 (2022)]. | first few overtones probe the event horizon geometry |
in this paper, we obtain a bulk dual to the low energy sector of the syk model, including syk model with u(1) charge, by kaluza-klein (kk) reduction from three dimensions. we show that kk reduction of the 3d einstein action plus its boundary term gives the jackiw-teitelboim (jt) model in 2d with the appropriate 1d boundary term. the size of the kk radius gets identified with the value of the dilaton in the resulting near-ads2 geometry. in presence of u(1) charge, the 3d model additionally includes a u(1) chern-simons (cs) action. in order to describe a boundary theory with non-zero chemical potential, we also introduce a coupling between cs gauge field and bulk gravity. the 3d cs action plus the new coupling term with appropriate boundary terms reduce in two dimensions to a bf-type action plus a source term and boundary terms. the kk reduced 2d theory represents the soft sector of the charged syk model. the pseudo-nambu-goldstone modes of combined diff/sl(2, &r;) and u(1)local/u(1) transformations are represented by combined large diffeomorphisms and large gauge transformations. the effective action of the former is reproduced by the action cost of the latter in the bulk dual, after appropriate identification of parameters. we compute chaotic correlators from the bulk and reproduce the result that the contribution from the "boundary photons" corresponds to zero liapunov exponent. | holographic dual to charged syk from 3d gravity and chern-simons |
we obtain an exact kerr-like black hole solution by solving the corresponding gravitational field equations in einstein-bumblebee gravity model where lorentz symmetry is spontaneously broken once a vector field acquires a vacuum expectation value. results are presented for the purely radial lorentz symmetry breaking. in order to study the effects of this breaking, we consider the black hole shadow and find that the radial of the unstable spherical orbit on the equatorial plane rc decreases with the lorentz breaking constant ℓ >0 , and increases with ℓ <0 . these shifts are similar to those of einstein-aether black hole. the effect of the lv parameter on the black hole shadow is that it accelerates the appearance of shadow distortion, and could be detected by the new generation of gravitational antennas. | exact kerr-like solution and its shadow in a gravity model with spontaneous lorentz symmetry breaking |
in this work, we obtain uncharged∖charged kiselev-like black holes as a new class of black hole solutions surrounded by perfect fluid in the context of rastall theory. then, we study the specific cases of the uncharged∖charged black holes surrounded by regular matter like dust and radiation, or exotic matter like quintessence, cosmological constant and phantom fields. by comparing the kiselev-like black hole solutions in rastall theory with the kiselev black hole solutions in gr, we find an effective perfect fluid behavior for the black hole's surrounding field. it is shown that the corresponding effective perfect fluid has interesting characteristic features depending on the different ranges of the parameters in rastall theory. for instance, kiselev-like black holes surrounded by regular matter in rastall theory may be considered as kiselev black holes surrounded by exotic matter in gr, or kiselev-like black holes surrounded by exotic matter in rastall theory may be considered as kiselev black holes surrounded by regular matter in gr. | black hole solutions surrounded by perfect fluid in rastall theory |
the role played by the mutual information of subsystems on the page curve is explored in this paper. with the total system consisting of the black hole and radiation, together with the inclusion of island, we observe that the vanishing of mutual information between b+ and b- which in turn means the disconnected phase of the entanglement wedge corresponding to b+∪b- , yields a time scale of the order of scrambling time. this results in a time independent expression for the fine grained entropy of hawking radiation consistent with the correct page curve. we also find corrections to this entropy and page time which are logarithmic and inverse power law in form. | mutual information, islands in black holes and the page curve |
ultralight bosons can affect the dynamics of spinning black holes (bhs) via superradiant instability, which can lead to a time evolution of the supermassive bh shadow. we study prospects for witnessing the superradiance-induced bh shadow evolution, considering ultralight vector and tensor fields. we introduce two observables sensitive to the shadow time-evolution: the shadow drift, and the variation in the azimuthal angle lapse associated to the photon ring autocorrelation. the two observables are shown to be highly complementary, depending on the observer's inclination angle. focusing on the supermassive object sgr a⋆ we show that both observables can vary appreciably over human timescales of a few years in the presence of superradiant instability, leading to signatures which are well within the reach of the event horizon telescope for realistic observation times (but benefiting significantly from extended observation periods) and paving the way towards probing ultralight bosons in the ∼10-17 ev mass range. | superradiant evolution of the shadow and photon ring of sgr a⋆ |
we employ the "kmoc" formalism of [1] to compute classical momentum deflections of spinning bodies with arbitrary spin orientations up to next-to-leading order (one loop). we do this in electrodynamics and gravity. the final result, valid for generic masses, is true for all spins at tree level and up to second (fourth) spin order for the electromagnetic (gravity) case at one loop. furthermore, emphasis is given to the probe limit scenario where our results extend to all spin orders in the heavy source, even at next-to-leading order. we carry out our computations both using a unitarity based framework and feynman diagrammatic approach which relies on scattering amplitudes computed on fixed backgrounds. | nlo deflections for spinning particles and kerr black holes |
three-dimensional einstein gravity with a negative cosmological constant admits stationary black holes that are not necessarily spherically symmetric. we propose boundary conditions for the near-horizon region of these black holes that lead to a surprisingly simple near-horizon symmetry algebra consisting of two affine u ^(1 ) current algebras. the symmetry algebra is essentially equivalent to the heisenberg algebra. the associated charges give a specific example of "soft hair" on the horizon, as defined by hawking, perry and strominger. we show that soft hair does not contribute to the bekenstein-hawking entropy of bañados-teitelboim-zanelli black holes and "black flower" generalizations. from the near-horizon perspective the conformal generators at asymptotic infinity appear as composite operators, which we interpret in the spirit of black hole complementarity. another remarkable feature of our boundary conditions is that they are singled out by requiring that the whole spectrum is compatible with regularity at the horizon, regardless of the value of the global charges like mass or angular momentum. finally, we address black hole microstates and generalizations to cosmological horizons. | soft heisenberg hair on black holes in three dimensions |
a new formalism for thermodynamics of ads black holes called the restricted phase space thermodynamics (rpst) is proposed. the construction is based on top of visser's holographic thermodynamics, but with the ads radius fixed as a constant. thus the rpst is free of the (p, v) variables but inherits the central charge and chemical potential as a new pair of conjugate thermodynamic variables. in this formalism, the euler relation and the gibbs-duhem equation hold simultaneously with the first law of black hole thermodynamics, which guarantee the appropriate homogeneous behaviors for the black hole mass and the intensive variables. the formalism is checked in detail in the example case of four-dimensional reissner-nordström anti-de sitter black hole in einstein-maxwell theory, in which some interesting thermodynamic behaviors are revealed. | restricted phase space thermodynamics for ads black holes via holography |
the classical scattering of spinning objects is well described by the spinor-helicity formalism for heavy particles. using these variables, we derive spurious-pole-free, all-spin opposite-helicity compton amplitudes (factorizing on physical poles to the minimal, all-spin three-point amplitudes of ref. \cite{arkani-hamed:2017jhn}) in the classical limit for qed, qcd, and gravity. the cured amplitudes are subject to deformations by contact terms, the vast majority of whose contributions we can fix by imposing a relation between spin structures -- motivated by lower spin multipoles of black hole scattering -- at the second post-minkowskian (2pm) order. for qed and gravity, this leaves a modest number of unfixed coefficients parametrizing contact-term deformations, while the qcd amplitude is uniquely determined. our gravitational compton amplitude allows us to push the state-of-the-art of spinning-2pm scattering to any order in the spin vectors of both objects; we present results here and in the auxiliary file \texttt{2pmspin8aux.nb} up to eighth order in the spin vectors. interestingly, despite leftover coefficients in the compton amplitude, imposing the aforementioned relation between spin structures uniquely fixes some higher-spin parts of the 2pm amplitude. | searching for kerr in the 2pm amplitude |
recently, in various theoretical works, path-breaking progress has been made in recovering the well-known page curve of an evaporating black hole with quantum extremal islands, proposed to solve the long-standing black hole information loss problem related to the unitarity issue. motivated by this concept, in this paper, we study cosmological circuit complexity in the presence (or absence) of quantum extremal islands in negative (or positive) cosmological constant with radiation in the background of friedmann-lemai^tre-robertson-walker (flrw) space-time, i.e., the presence and absence of islands in anti de sitter and the de sitter space-time having so(2, 3) and so(1, 4) isometries, respectively. without using any explicit details of any gravity model, we study the behavior of the circuit complexity function with respect to the dynamical cosmological solution for the scale factors for the above mentioned two situations in flrw space-time using squeezed state formalism. by studying the cosmological circuit complexity, out-of-time ordered correlators, and entanglement entropy of the modes of the squeezed state, in different parameter space, we conclude the non-universality of these measures. their remarkably different features in the different parameter space suggests their dependence on the parameters of the model under consideration. | circuit complexity from cosmological islands |
we study the holographic complexity of einstein-maxwell-dilaton gravity using the recently proposed "complexity = volume" and "complexity = action" dualities. the model we consider has a ground state that is represented in the bulk via a so-called hyperscaling violating geometry. we calculate the action growth of the wheeler-dewitt patch of the corresponding black hole solution at non-zero temperature and find that, depending on the parameters of the theory, there is a parametric enhancement of the action growth rate relative to the conformal field theory result. we match this behavior to simple tensor network models which can capture aspects of hyperscaling violation. we also exhibit the switchback effect in complexity growth using shockwave geometries and comment on a subtlety of our action calculations when the metric is discontinuous at a null surface. | holographic complexity of einstein-maxwell-dilaton gravity |
expanding on the recent derivation of tidal actions for scalar particles, we present here the action for a tidally deformed spin-1/2 particle. focusing on operators containing two powers of the weyl tensor, we combine the hilbert series with an on-shell amplitude basis to construct the tidal action. with the tidal action in hand, we compute the leading-post-minkowskian tidal contributions to the spin-1/2-spin-1/2 amplitude, arising at o (g2). our amplitudes provide evidence that the observed long range spin-universality for the scattering of two point particles extends to the scattering of tidally deformed objects. from the scattering amplitude we find the conservative two-body hamiltonian, linear and angular impulses, eikonal phase, spin kick, and aligned-spin scattering angle. we present analogous results in the electromagnetic case along the way. | tidal effects for spinning particles |
we explain in detail how to calculate the gravitational mass and angular momentum multipoles of the most general non-extremal four-dimensional black hole with four magnetic and four electric charges. we also calculate these multipoles for generic supersymmetric four-dimensional microstate geometries and multi-center solutions. both for kerr black holes and bps black holes many of these multipoles vanish. however, if one embeds these black holes in string theory and slightly deforms them, one can calculate an infinite set of ratios of vanishing multipoles which remain finite as the deformation is taken away, and whose values are independent of the direction of deformation. for supersymmetric black holes, we can also compute these ratios by taking the scaling limit of multi-center solutions, and for certain black holes the ratios computed using the two methods agree spectacularly. for the kerr black hole, these ratios pose strong constraints on the parameterization of possible deviations away from the kerr geometry that should be tested by future gravitational wave interferometers. | black holes lessons from multipole ratios |
a number of recent works have argued that quantum complexity, a well-known concept in computer science that has re-emerged recently in the context of the physics of black holes, may be used as an efficient probe of novel phenomena such as quantum chaos and even quantum phase transitions. in this article, we provide further support for the latter, using a 1-dimensional p-wave superconductor — the kitaev chain — as a prototype of a system displaying a topological phase transition. the hamiltonian of the kitaev chain manifests two gapped phases of matter with fermion parity symmetry; a trivial strongly-coupled phase and a topologically non-trivial, weakly-coupled phase with majorana zero-modes. we show that krylov-complexity (or, more precisely, the associated spread-complexity) is able to distinguish between the two and provides a diagnostic of the quantum critical point that separates them. we also comment on some possible ambiguity in the existing literature on the sensitivity of different measures of complexity to topological phase transitions. | spread complexity and topological transitions in the kitaev chain |
in this paper, the new formalism of thermodynamic geometry proposed in hosseini mansoori and mirza (2019) is employed in investigating phase transition points and the critical behavior of a gauss-bonnet-ads black hole in four dimensional spacetime. in this regard, extrinsic and intrinsic curvatures of a certain kind of hypersurface immersed in the thermodynamic manifold contain information about stability/instability of heat capacities. we, therefore, calculate the intrinsic curvature of the q-zero hypersurface for a four-dimensional neutral gauss bonnet black hole case in the extended phase space. interestingly, intrinsic curvature can be positive for small black holes at low temperature, which indicates a repulsive interaction among black hole microstructures. this finding is in contrast with the five-dimensional neutral gauss bonnet black hole with only dominant attractive interaction between its microstructures. | thermodynamic geometry of the novel 4-d gauss-bonnet ads black hole |
a reissner-nordström black hole (bh) is superradiantly unstable against spherical perturbations of a charged scalar field enclosed in a cavity, with a frequency lower than a critical value. we use numerical relativity techniques to follow the development of this unstable system—dubbed a charged bh bomb—into the nonlinear regime, solving the full einstein-maxwell-klein-gordon equations, in spherical symmetry. we show that (i) the process stops before all the charge is extracted from the bh, and (ii) the system settles down into a hairy bh: a charged horizon in equilibrium with a scalar field condensate, whose phase is oscillating at the (final) critical frequency. for a low scalar field charge q , the final state is approached smoothly and monotonically. for large q , however, the energy extraction overshoots, and an explosive phenomenon, akin to a bosenova, pushes some energy back into the bh. the charge extraction, by contrast, does not reverse. | explosion and final state of an unstable reissner-nordström black hole |
recent work has shown how to understand the page curve of an evaporating black hole from replica wormholes. however, more detailed information about the structure of its quantum state is needed to fully understand the dynamics of black hole evaporation. here we study entanglement negativity, an important measure of quantum entanglement in mixed states, in a couple of toy models of evaporating black holes. we find four phases dominated by different types of geometries: the disconnected, cyclically connected, anti-cyclically connected, and pairwise connected geometries. the last of these geometries are new replica wormholes that break the replica symmetry spontaneously. we also analyze the transitions between these four phases by summing more generic replica geometries using a schwinger-dyson equation. in particular, we find enhanced corrections to various negativity measures near the transition between the cyclic and pairwise phase. | replica wormholes and holographic entanglement negativity |
the properties of compact binaries, such as masses and spins, are imprinted in the gravitational waves (gws) they emit and can be measured using parametrized waveform models. accurately and efficiently describing the complicated precessional dynamics of the various angular momenta of the system in these waveform models is the object of active investigation. one of the key models extensively used in the analysis of ligo and virgo data is the single-precessing-spin waveform model imrphenompv2. in this article we present a new model imrphenompv3, which includes the effects of two independent spins in the precession dynamics. whereas imrphenompv2 utilizes a single-spin frequency-dependent post-newtonian rotation to describe precession effects, the improved model, imrphenompv3, employs a double-spin rotation that is based on recent developments in the description of precessional dynamics. besides double-spin precession, the improved model benefits from a more accurate description of precessional effects. we validate our new model against a large set of precessing numerical-relativity simulations. we find that imrphenompv3 has better agreement with the inspiral portion of precessing binary-black-hole simulations and is more robust across a larger region of the parameter space than imrphenompv2. as a first application we analyze the gravitational-wave event gw151226 with an efficient frequency-domain waveform model that describes two-spin precession. within statistical uncertainty our results are consistent with published results. imrphenompv3 will allow studies of the measurability of individual spins of binary black holes using gws and can be used as a foundation upon which to build further improvements, such as modeling precession through merger, extending to higher multipoles, and including tidal effects. | phenomenological model for the gravitational-wave signal from precessing binary black holes with two-spin effects |
black hole (bh) shadows can be used to probe new physics in the form of ultralight particles via the phenomenon of superradiant instability. by directly affecting the bh mass and spin, superradiance can lead to a time evolution of the bh shadow, which nonetheless has been argued to be unobservable through very-long-baseline interferometry (vlbi) over realistic observation time scales. we revisit the superradiance-induced bh shadow evolution including the competing effects of gas accretion and gravitational wave (gw) emission and, as a first step towards modeling realistic new physics scenarios which predict the existence of multiple ultralight species, we study the system in the presence of two ultralight bosons, whose combined effect could help reduce the shadow evolution time scale. we find that accretion and gw emission play a negligible role in our results (justifying previous simplified analyses), and that contrary to our intuition the inclusion of an additional ultralight boson does not shorten the bh shadow evolution time scale and hence improve detection prospects. however, we point out an important subtlety concerning the observationally meaningful definition of the superradiance-induced bh shadow evolution time scale, which reduces the latter by about an order of magnitude, opening up the possibility of observing the superradiance-induced bh shadow evolution with upcoming vlbi arrays, provided angular resolutions just below the μ as level can be reached. as a concrete example, we show that the angular size of the shadow of sgra* can change by up to 0.6 μ as over a period as short as 16 years, which further strengthens the scientific case for targeting the shadow of sgra* with next-generation vlbi arrays. | superradiance evolution of black hole shadows revisited |
we construct supersymmetric [inline-graphic not available: see fulltext]solutions of d = 6 gauged supergravity, where [inline-graphic not available: see fulltext] is a two-dimensional orbifold known as a spindle. these uplift to solutions of massive type iia supergravity using a general prescription, that we describe. we argue that these solutions correspond to the near-horizon limit of a system of nf d8-branes, together with n d4-branes wrapped on a spindle, embedded as a holomorphic curve inside a calabi-yau three-fold. the dual field theories are d = 3, n = 2 scfts that arise from a twisted compactification of the d = 5, n = 1 usp(2n) gauge theory. we show that the holographic free energy associated to these solutions is reproduced by extremizing an off- shell free energy, that we conjecture to arise in the large n limit of the localized partition function of the d = 5 theories on [inline-graphic not available: see fulltext]. we formulate a universal proposal for a class of off-shell free energies, whose extremization reproduces all previous results for branes wrapped on spindles, as well as on genus g riemann surfaces σg. we further illustrate this proposal discussing d4-branes wrapped on [inline-graphic not available: see fulltext], for which we present a supersymmetric [inline-graphic not available: see fulltext] solution of d = 6 gauged supergravity along with the associated entropy function. | d4-branes wrapped on a spindle |
we propose a novel method to test the binary black hole nature of compact binaries detectable by gravitational wave (gw) interferometers and, hence, constrain the parameter space of other exotic compact objects. the spirit of the test lies in the "no-hair" conjecture for black holes where all properties of a kerr black hole are characterized by its mass and spin. the method relies on observationally measuring the quadrupole moments of the compact binary constituents induced due to their spins. if the compact object is a kerr black hole (bh), its quadrupole moment is expressible solely in terms of its mass and spin. otherwise, the quadrupole moment can depend on additional parameters (such as the equation of state of the object). the higher order spin effects in phase and amplitude of a gravitational waveform, which explicitly contains the spin-induced quadrupole moments of compact objects, hence, uniquely encode the nature of the compact binary. thus, we argue that an independent measurement of the spin-induced quadrupole moment of the compact binaries from gw observations can provide a unique way to distinguish binary bh systems from binaries consisting of exotic compact objects. | testing the binary black hole nature of a compact binary coalescence |
on 14 september 2015, a gravitational wave signal from a coalescing black hole binary system was observed by the advanced ligo detectors. this paper describes the transient noise backgrounds used to determine the significance of the event (designated gw150914) and presents the results of investigations into potential correlated or uncorrelated sources of transient noise in the detectors around the time of the event. the detectors were operating nominally at the time of gw150914. we have ruled out environmental influences and non-gaussian instrument noise at either ligo detector as the cause of the observed gravitational wave signal. | characterization of transient noise in advanced ligo relevant to gravitational wave signal gw150914 |
the field equations for scalar-tensor-vector gravity (stvg) or modified gravity (mog) have a static, spherically symmetric black hole solution determined by the mass with two horizons. the strength of the gravitational constant is where is a parameter. a regular singularity-free mog solution is derived using a nonlinear field dynamics for the repulsive gravitational field component and a reasonable physical energy-momentum tensor. the kruskal-szekeres completion of the mog black hole solution is obtained. the kerr-mog black hole solution is determined by the mass , the parameter and the spin angular momentum . the equations of motion and the stability condition of a test particle orbiting the mog black hole are derived, and the radius of the black hole photosphere and the shadows cast by the schwarzschild-mog and kerr-mog black holes are calculated. a traversable wormhole solution is constructed with a throat stabilized by the repulsive component of the gravitational field. | black holes in modified gravity (mog) |
we consider light propagation in a nonmagnetized pressureless plasma around a kerr black hole. we find the necessary and sufficient condition the plasma electron density has to satisfy to guarantee that the hamilton-jacobi equation for the light rays is separable, i.e., that a generalized carter constant exists. for all cases where this condition is satisfied we determine the photon region; i.e., the region in the spacetime where spherical light rays exist. a spherical light ray is a light ray that stays on a sphere r =constant (in boyer-lindquist coordinates). based on these results, we calculate the shadow of a kerr black hole under the influence of a plasma that satisfies the separability condition. more precisely, we derive an analytical formula for the boundary curve of the shadow on the sky of an observer that is located anywhere in the domain of outer communication. several examples are worked out. | light propagation in a plasma on kerr spacetime: separation of the hamilton-jacobi equation and calculation of the shadow |
we propose a new example of entanglement knitting spacetime together, satisfying a series of checks of the corresponding von neumann and renyi entropies. the conjectured dual of de sitter in d + 1 dimensions involves two coupled cft sectors constrained by residual d-dimensional gravity. in the d = 2 case, the gravitational constraints and the cft spectrum are relatively tractable. we identify a finite portion of each cft hilbert space relevant for de sitter. its maximum energy level coincides with the transition to the universal cardy behavior for theories with a large central charge and a sparse light spectrum, derived by hartman, keller, and stoica. significant interactions between the two cfts, derived previously for other reasons, suggest a maximally mixed state upon tracing out one of the two sectors; we derive this by determining the holographic renyi entropies. the resulting entanglement entropy matches the gibbons-hawking formula for de sitter entropy, including the numerical coefficient. finally, we interpret the gibbons-hawking horizon entropy in terms of the ryu-takayanagi entropy, and explore the time evolution of the entanglement entropy. | de sitter holography and entanglement entropy |
using "complexity=action" proposal we study the growth rate of holographic complexity for lifshitz and hyperscaling violating geometries. we will consider both one and two sided black branes in an einstein-maxwell-dilaton gravitational theory. we find that in either case lloyd's bound is violated and the rate of growth of complexity saturate to a value which is greater than twice the mass of the corresponding black brane. this value reduces to the mass of the black brane in the isotropic case. we show that in two sided black brane the saturation happens from above while for one sided black brane it happens from below. | complexity growth with lifshitz scaling and hyperscaling violation |
we develop massive higher-spin theory as a framework for describing dynamics of rotating compact objects, such as kerr black holes. in this paper, we explore gauge interactions up to quartic order and corresponding compton amplitudes of higher-spin massive objects coupled to electromagnetism and yang-mills theory. their classical counterparts are known as root-kerr gauge-theory solutions, whose amplitudes are closely related to those of kerr black holes. we use three distinct approaches: (i) massive higher-spin gauge symmetry to introduce cubic interactions for all spins and the quartic interactions up to spin 3, which is implemented both off shell and via ward identities; (ii) a chiral higher-spin approach to construct quartic lagrangians with correct degrees of freedom to all spins; (iii) on-shell functional patterns before and after taking the classical limit to constrain the compton amplitudes. as final results, we arrive at simple local formulae for the candidate root-kerr compton amplitudes both in the quantum regime and classical limit, to all orders in spin. this is a precursor to the gravitational kerr case, which is presented in a follow-up paper. | from higher-spin gauge interactions to compton amplitudes for root-kerr |
we propose an algebraic definition of er=epr in the $g_n \to 0$ limit, which associates bulk spacetime connectivity/disconnectivity to the operator algebraic structure of a quantum gravity system. the new formulation not only includes information on the amount of entanglement, but also more importantly the structure of entanglement. we give an independent definition of a quantum wormhole as part of the proposal. this algebraic version of er=epr sheds light on a recent puzzle regarding spacetime disconnectivity in holographic systems with ${\cal o}(1/g_{n})$ entanglement. we discuss the emergence of quantum connectivity in the context of black hole evaporation and further argue that at the page time, the black hole-radiation system undergoes a transition involving the transfer of an emergent type iii$_{1}$ subalgebra of high complexity operators from the black hole to radiation. we argue this is a general phenomenon that occurs whenever there is an exchange of dominance between two competing quantum extremal surfaces. | algebraic er=epr and complexity transfer |
double holography offers a profound understanding of the island formula by describing a gravitational system on adsd coupled to a conformal field theory on &r;1,d−1, dual to an adsd+1 spacetime with an end-of-the-world (eow) brane. in this work, we extend the proposal in [12] by considering that the dual bulk spacetime has two eow branes: one with a gravitational system and the other with a thermal bath. we demonstrate an equivalence between this proposal and the wedge holographic theory. we examine it in both anti-de sitter gravity and de sitter gravity by calculating the entanglement entropy of the hawking radiation. finally, we employ the doubly holographic model to verify the formula for the entanglement entropy in a subregion within conformally flat spacetime. | island formula in planck brane |
we investigate how the complexity=anything observables proposed by [1, 2] can be used to investigate the interior geometry of ads black holes. in particular, we illustrate how the flexibility of the complexity=anything approach allows us to systematically probe the geometric properties of black hole singularities. we contrast our results for the ads schwarzschild and ads reissner-nordström geometries, i.e., for uncharged and charged black holes, respectively. in the latter case, the holographic complexity observables can only probe the interior up to the inner horizon. | complexity=anything: singularity probes |
we study the canonical ads /cft correspondence between 4d s u (n ) n =4 super yang-mills theory (sym) and type iib superstring theory on ads5×s5. we analyze the supersymmetric index of the n =4 sym on s1×m3 which counts supersymmetric states with fixed quantum numbers. we compute an asymptotic behavior of the index in the limit of shrinking s1 for any n by a refinement of the 4d supersymmetric cardy formula. the asymptotic behavior for the superconformal index case (m3=s3) at large n agrees with the bekenstein-hawking entropy of a rotating electrically charged bogomolnyi-prasad-sommerfeld (bps) black hole in ads5 via a legendre transformation as recently shown in the literature. we also find that the agreement formally persists for finite n if we slightly modify the ads /cft dictionary between the newton constant and n . this implies the existence of a nonrenormalization property of the black hole entropy against quantum corrections. we also study the cases with other gauge groups and additional matter and the orbifold n =4 sym. it turns out that the entropies of all the cft examples in this paper are universally given by 2 π √{q1q2+q1q3+q2q3-2 c (j1+j2) } with charges q1 ,2 ,3, angular momenta j1 ,2, and central charge c . the results for other m3 make predictions to the gravity side. | quantum black hole entropy from 4d supersymmetric cardy formula |
it is widely believed that exact global symmetries do not exist in theories that admit quantum black holes. here we propose a way to quantify the degree of global symmetry violation in the hawking radiation of a black hole by using certain relative entropies. while the violations of global symmetry that we consider are non-perturbative effects, they nevertheless give o (1) contributions to the relative entropy after the page time. furthermore, using "island" formulas, these relative entropies can be computed within semi-classical gravity, which we demonstrate with explicit examples. these formulas give a rather precise operational sense to the statement that a global charge thrown into an old black hole will be lost after a scrambling time.the relative entropies considered here may also be computed using a replica trick. at integer replica index, the global symmetry violating effects manifest themselves as charge flowing through the replica wormhole. | signatures of global symmetry violation in relative entropies and replica wormholes |
we investigate the null geodesics and the shadow cast by the kerr-newman-kiselev-letelier (knkl) black hole for the equation of state parameter ωq=-2 /3 and for different values of the spacetime parameters, including the quintessence parameter γ , the cloud of string (cs) parameter b, the spin parameter a and the charge q of the black hole. we notice that for the increasing values of the parameters γ and b the size of the shadow of the knkl black hole increases and consequently the strength of the gravitational field of the black hole increases. on the other hand with increase in the charge q of the black hole the size of the shadow of the black hole decreases. further with the increase in the values of the spin parameter a of the knkl black hole, we see that the distortion of the shadow of the black hole becomes more prominent. moreover we use the data released by the event horizon telescope (eht) collaboration, to restrict the parameters b and γ for the knkl black hole, using the shadow cast by the knkl black hole. to this end, we also explore the relation between the typical shadow radius and the equatorial and polar quasinormal mods (qnms) for the knkl black hole and extend this correspondence to non-asymptotically flat spacetimes. we also study the emission energy rate from the knkl black hole for the various spacetime parameters, and observe that it increases for the increasing values of both the parameters γ and b for fixed charge-to-mass and spin-to-mass ratios of the knkl black hole. finally, we investigate the effects of plasma on the photon motion, size and shape of the shadow cast by the knkl black hole. while keeping the spacetime parameters fixed, we notice that with increase in the strength of the plasma medium the size of the shadow of the knkl black hole decreases and therefore the intensity of the gravitational field of the knkl black hole decreases in the presence of plasma. | shadow and quasinormal modes of the kerr-newman-kiselev-letelier black hole |
we investigate the fine-grained entropy of the de sitter cosmological horizon. starting from three-dimensional pure de sitter space, we consider a partial reduction approach, which supplies an auxiliary system acting as a heat bath both at i + and inside the static patch. this allows us to study the time-dependent entropy of radiation collected for both observers in the out-of-equilibrium unruh-de sitter state, analogous to black hole evaporation for a cosmological horizon. central to our analysis in the static patch is the identification of a weakly gravitating region close to the past cosmological horizon; this is suggestive of a relation between observables at future infinity and inside the static patch. we find that in principle, while the meta-observer at i + naturally observes a pure state, the static patch observer requires the use of the island formula to reproduce a unitary page curve. however, in practice, catastrophic backreaction occurs at the page time, and neither observer will see unitary evaporation. | no page curves for the de sitter horizon |
during the past decades, theorists have been studying quantum mechanical systems that are believed to describe black holes. we review one of the simplest examples. it involves a collection of interacting oscillators and majorana fermions. it is conjectured to describe a black hole in an emergent universe governed by einstein equations. based on previous numerical computations, we make an estimate of the necessary number of qubits necessary to see some black hole features. | a simple quantum system that describes a black hole |
a manifestation of the black hole information loss problem is that the two-point function of probe operators in a large anti-de sitter black hole decays in time, whereas, on the boundary cft, it is expected to be an almost periodic function of time. we point out that the decay of the two-point function (clustering in time) holds important clues to the nature of observable algebras, states, and dynamics in quantum gravity.we call operators that cluster in time "mixing" and explore the necessary and sufficient conditions for mixing. the information loss problem is a special case of the statement that in type i algebras, there exists no mixing operators. we prove that, in a thermofield double state (kms state), if mixing operators form an algebra (close under multiplication), the resulting algebra must be a von neumann type iii1 factor. in other words, the physically intuitive requirement that all nonconserved operators should exponentially mix is so strong that it fixes the observable algebra to be an exotic algebra called a type iii1 factor. more generally, for an arbitrary out-of-equilibrium state of a general quantum system (von neumann algebra), we show that if the set of operators that mix under modular flow forms an algebra, it is a type iii1 von neumann factor.in a theory of generalized free fields (gff), we show that if the two-point function clusters in time, all operators are mixing, and the algebra is a type iii1 factor. for example, in 𝒩 = 4 sym, above the hawking-page phase transition, clustering of the single trace operators implies that the algebra is a type iii1 factor, settling a recent conjecture of leutheusser and liu. we explicitly construct the c∗-algebra and von neumann subalgebras of gff associated with time bands and, more generally, open sets of the bulk spacetime using the hkll reconstruction map. | information loss, mixing and emergent type iii1 factors |
we study gravitational absorption effects using effective on-shell scattering amplitudes. we develop an in-in probability-based framework involving plane- and partial-wave coherent states for the incoming wave to describe the interaction of the wave with a black hole or another compact object. we connect this framework to a simplified single-quantum analysis. the basic ingredients are mass-changing three-point amplitudes, which model the leading absorption effects and a spectral-density function of the black hole. as an application, we consider a non-spinning black hole that may start spinning as a consequence of the dynamics. the corresponding amplitudes are found to correspond to covariant spin-weighted spherical harmonics, the properties of which we formulate and make use of. we perform a matching calculation to general-relativity results at the cross-section level and derive the effective absorptive three-point couplings. they are found to behave as o (gnewtons+1), where s is the spin of the outgoing massive state. | gravitational partial-wave absorption from scattering amplitudes |
according to bekenstein's area law, the black hole entropy is identified holographically with one quarter of the horizon area. however, it is commonly believed that such a law is only valid in einstein's theory and that higher curvature corrections generically give rise to its modifications. this is, for example, the case of black holes in lovelock gravities, or their four-dimensional cousins in the recently discovered 4d scalar-tensor gauss-bonnet gravity where one naively "finds" (classical) logarithmic corrections to the bekenstein's law. in this paper we argue that such logarithmic corrections originate from ignoring the shift symmetry of the 4d gauss-bonnet gravity. when this symmetry is properly taken into account, there is no longer any departure from the area law in this theory. moreover, the first law remains valid upon modifying the black hole temperature, which can be derived via the euclidean grand canonical ensemble (brown-york) procedure, but is no longer given by the surface gravity. interestingly, we show that upon similar modification of the black hole temperature the area law can also prevail for black holes in higher-dimensional lovelock gravities. | can bekenstein's area law prevail in modified theories of gravity? |
previously the linearized stress tensor of a stationary kerr black hole has been used to determine some of the values of gravitational couplings for a spinning black hole to linear order in the riemann tensor in the action (worldline or quantum field theory). in particular, the couplings on operators containing derivative structures of the form $(s\cdot\nabla)^n$ acting on the riemann tensor were fixed, with $s^\mu$ the spin vector of the black hole. in this paper we find that the kerr solution determines all of the multipole moments in the sense of dixon of a stationary spinning black hole and that these multipole moments determine all linear in $r$ couplings. for example, additional couplings beyond the previously mentioned are fixed on operators containing derivative structures of the form $s^{2n}(p\cdot\nabla)^{2n}$ acting on the riemann tensor with $p^\mu$ the momentum vector of the black hole. these additional operators do not contribute to the three-point amplitude, and so do no contribute to the linearized stress tensor for a stationary black hole. however, we find that they do contribute to the compton amplitude. additionally, we derive formal expressions for the electromagnetic and gravitational compton amplitudes of generic spinning bodies to all orders in spin in the worldline formalism and evaluated expressions for these amplitudes to order $s^3$ in electromagnetism and order $s^5$ in gravity. | dynamical implications of the kerr multipole moments for spinning black holes |
it has long been known that the coarse-grained approximation to the black hole density of states can be computed using classical euclidean gravity. in this work we argue for another entry in the dictionary between euclidean gravity and black hole physics, namely that euclidean wormholes describe a coarse-grained approximation to the energy level statistics of black hole microstates. to do so we use the method of constrained instantons to obtain an integral representation of wormhole amplitudes in einstein gravity and in full-fledged ads/cft. these amplitudes are non-perturbative corrections to the two-boundary problem in ads quantum gravity. the full amplitude is likely uv sensitive, dominated by small wormholes, but we show it admits an integral transformation with a macroscopic, weakly curved saddle-point approximation. the saddle is the "double cone" geometry of saad, shenker, and stanford, with fixed moduli. in the boundary description this saddle appears to dominate a smeared version of the connected two-point function of the black hole density of states, and suggests level repulsion in the microstate spectrum. using these methods we further study euclidean wormholes in pure einstein gravity and in iib supergravity on euclidean ads5× s5. we address the perturbative stability of these backgrounds and study brane nucleation instabilities in 10d supergravity. in particular, brane nucleation instabilities of the euclidean wormholes are lifted by the analytic continuation required to obtain the lorentzian spectral form factor from gravity. our results indicate a factorization paradox in ads/cft. | wormholes and black hole microstates in ads/cft |
we construct an infinite family of smooth asymptotically-flat supergravity solutions that have the same charges and angular momenta as general supersymmetric d1-d5-p black holes, but have no horizon. these solutions resemble the corresponding black hole to arbitrary accuracy outside of the horizon: they have asymptotically flat regions, {ads}_3× s^3 throats and very-near-horizon ads2 throats, which however end in a smooth cap rather than an event horizon. the angular momenta of the solutions are general, and in particular can take arbitrarily small values. upon taking the {ads}_3× s^3 decoupling limit, we identify the holographically-dual cft states. | asymptotically-flat supergravity solutions deep inside the black-hole regime |
i provide a frequency domain reduced order model (rom) for the aligned-spin effective-one-body model "seobnrv2" for data analysis with second- and third-generation ground-based gravitational wave (gw) detectors. seobnrv2 models the dominant mode of the gws emitted by the coalescence of black hole binaries. the large physical parameter space (dimensionless spins -1 ≤χi≤0.99 and symmetric mass ratios 0.01 ≤η ≤0.25 ) requires sophisticated reduced order modeling techniques, including patching in the parameter space and in frequency. i find that the time window over which the inspiral-plunge and the merger-ringdown waveform in seobnrv2 are connected has a discontinuous dependence on the parameters when the spin parameter χ =0.8 or the symmetric mass ratio η ∼0.083 . this discontinuity increases resolution requirements for the rom. the rom can be used for compact binary systems with total masses of 2 m⊙ or higher for the advanced ligo design sensitivity and a 10 hz lower cutoff frequency. the rom has a worst mismatch against seobnrv2 of ∼1 %, but in general mismatches are better than ∼0.1 %. the rom is crucial for key data analysis applications for compact binaries, such as gw searches and parameter estimation carried out within the ligo scientific collaboration. | frequency domain reduced order model of aligned-spin effective-one-body waveforms with generic mass ratios and spins |
in this paper, we investigate the effect of supersymmetry on the symmetry classification of random matrix theory ensembles. we mainly consider the random matrix behaviors in the n=1 supersymmetric generalization of sachdev-ye-kitaev (syk) model, a toy model for two-dimensional quantum black hole with supersymmetric constraint. some analytical arguments and numerical results are given to show that the statistics of the supersymmetric syk model could be interpreted as random matrix theory ensembles, with a different eight-fold classification from the original syk model and some new features. the time-dependent evolution of the spectral form factor is also investigated, where predictions from random matrix theory are governing the late time behavior of the chaotic hamiltonian with supersymmetry. | supersymmetric syk model and random matrix theory |
the volume of the region inside the bulk ryu-takayanagi surface is a codimension-one object, and a natural generalization of holographic complexity to the case of subregions in the boundary qft. we focus on time-independent geometries, and study the properties of this volume in various circumstances. we derive a formula for computing the volume for a strip entangling surface and a general asymptotically ads bulk geometry. for an ads black hole geometry, the volume exhibits non-monotonic behaviour as a function of the size of the entangling region (unlike the behaviour of the entanglement entropy in this setup, which is monotonic). for setups in which the holographic entanglement entropy exhibits transitions in the bulk, such as global ads black hole, geometries dual to confining theories and disjoint entangling surfaces, the corresponding volume exhibits a discontinuous finite jump at the transition point (and so do the volumes of the corresponding entanglement wedges). we compute this volume discontinuity in several examples. lastly, we compute the codim-zero volume and the bulk action of the entanglement wedge for the case of a sphere entangling surface and pure ads geometry. | on volumes of subregions in holography and complexity |
ultralight bosons can induce superradiant instabilities in spinning black holes, tapping their rotational energy to trigger the growth of a bosonic condensate. possible observational imprints of these boson clouds include (i) direct detection of the nearly monochromatic (resolvable or stochastic) gravitational waves emitted by the condensate, and (ii) statistically significant evidence for the formation of "holes" at large spins in the spin versus mass plane (sometimes also referred to as "regge plane") of astrophysical black holes. in this work, we focus on the prospects of lisa and ligo detecting or constraining scalars with mass in the range ms∈[10-19,10-15] ev and ms∈[10-14,10-11] ev , respectively. using astrophysical models of black-hole populations calibrated to observations and black-hole perturbation theory calculations of the gravitational emission, we find that, in optimistic scenarios, ligo could observe a stochastic background of gravitational radiation in the range ms∈[2 ×10-13,10-12] ev , and up to 1 04 resolvable events in a 4-year search if ms∼3 ×10-13 ev . lisa could observe a stochastic background for boson masses in the range ms∈[5 ×10-19,5 ×10-16], and up to ∼103 resolvable events in a 4-year search if ms∼10-17 ev . lisa could further measure spins for black-hole binaries with component masses in the range [103,107]m⊙, which is not probed by traditional spin-measurement techniques. a statistical analysis of the spin distribution of these binaries could either rule out scalar fields in the mass range ∼[4 ×10-18,10-14] ev , or measure ms with ten percent accuracy if light scalars in the mass range ∼[10-17,10-13] ev exist. | gravitational wave searches for ultralight bosons with ligo and lisa |
the detection of gravitational waves from compact binary mergers by the ligo/virgo collaboration has, for the first time, allowed for tests of relativistic gravity in the strong, dynamical, and nonlinear regime. outside einstein's relativity, spinning black holes may be different from their general relativistic counterparts, and their merger may then lead to a modified ringdown. we study the latter and, for the first time, derive a modified teukolsky equation, i.e., a set of linear, decoupled differential equations that describe dynamical perturbations of non-kerr black holes for the radiative newman-penrose scalars ψ0 and ψ4. we first focus on non-ricci-flat, petrov type-d black hole backgrounds in modified gravity and derive the modified teukolsky equation through direct decoupling and through a new approach, proposed by chandrasekhar, that uses certain gauge conditions. we then extend this analysis to non-ricci-flat, petrov type-i black hole backgrounds in modified gravity, assuming they can be treated as a linear perturbation of petrov type-d , black hole backgrounds in general relativity by generalizing chandrasekhar's approach, and derive the decoupled modified teukolsky equation. we further show that our formalism can be extended beyond linear order in both modified gravity corrections and gravitational wave perturbations. our work lays the foundation to study the gravitational waves emitted in the ringdown phase of black hole coalescence in modified gravity for black holes of any spin. our work can also be extended to compute gravitational waves emitted by extreme mass-ratio binary inspirals in modified gravity. | perturbations of spinning black holes beyond general relativity: modified teukolsky equation |
generic models of regular black holes have separate outer and inner horizons, both with nonzero surface gravity. it has been shown that a nonzero inner horizon surface gravity results in exponential instability at the inner horizon controlled by this parameter. this phenomenon takes the name of "mass inflation instability", and its presence has put in question the physical viability of regular black holes as alternatives to their (singular) general relativity counterparts. in this paper, we show that it is possible to make the inner horizon surface gravity vanish, while maintaining the separation between horizons, and a non-zero outer horizon surface gravity. we construct specific geometries satisfying these requirements, and analyze their behavior under different kinds of perturbations, showing that the exponential growth characteristic of mass inflation instability is not present for these geometries. these "inner-extremal" regular black holes are thereby better behaved than singular black holes and generic regular black holes, thus providing a well-motivated alternative of interest for fundamental and phenomenological studies. | regular black holes without mass inflation instability |
in this paper, we study joule-thomson effects for charged ads black holes. we obtain inversion temperatures and curves. we investigate similarities and differences between van der waals fluids and charged ads black holes for the expansion. we obtain isenthalpic curves for both systems in the t- p plane and determine the cooling-heating regions. | joule-thomson expansion of the charged ads black holes |
the detection of gravitational waves from compact binary mergers by ligo has opened the era of gravitational wave astronomy, revealing a previously hidden side of the cosmos. to maximize the reach of the existing ligo observatory facilities, we have designed a new instrument able to detect gravitational waves at distances 5 times further away than possible with advanced ligo, or at greater than 100 times the event rate. observations with this new instrument will make possible dramatic steps toward understanding the physics of the nearby universe, as well as observing the universe out to cosmological distances by the detection of binary black hole coalescences. this article presents the instrument design and a quantitative analysis of the anticipated noise floor. | a cryogenic silicon interferometer for gravitational-wave detection |
in this whitepaper, i describe modern applications of effective field theory (eft) techniques to classical and quantum gravity, with relevance to problems in astrophysics and cosmology. as in applications of eft to high-energy, nuclear, or condensed matter physics, the wilsonian paradigm based on decoupling of short distance scales via renormalization group evolution remains a powerful organizing principle in the context of gravity. however, the presence of spacetime geometry brings in new elements ( non-trivial time-dependence, cosmological or black hole event horizons) which necessitate the introduction of novel field theoretic methods not usually encountered in applications of efts to physics at the energy and intensity frontiers. after a brief overview of recent developments in the application of eft methods to gravity, i will focus on the eft description of compact binary dynamics, including an overview of some of its applications to the experimental program in gravitational wave detection at ligo/virgo and other observatories. | effective field theories of gravity and compact binary dynamics: a snowmass 2021 whitepaper |
we construct new euclidean wormhole solutions in adsd+1 and discuss their role in uv-complete theories, without ensemble averaging. the geometries are interpreted as overlaps of ghz-like entangled states, which arise naturally from coarse graining the density matrix of a pure state in the dual cft. in several examples, including thin-shell collapsing black holes and pure black holes with an end-of-the-world brane behind the horizon, the coarse-graining map is found explicitly in cft terms, and used to define a coarse-grained entropy that is equal to one quarter the area of a time-symmetric apparent horizon. wormholes are used to derive the coarse-graining map and to study statistical properties of the quantum state. this reproduces aspects of the west coast model of 2d gravity and the large-c ensemble of 3d gravity, including a page curve, in a higher-dimensional context with generic matter fields. | coarse graining pure states in ads/cft |
in this paper, we study massive gravity in the presence of born-infeld nonlinear electrodynamics. first, we obtain metric function related to this gravity and investigate the geometry of the solutions and find that there is an essential singularity at the origin ( r = 0). it will be shown that due to contribution of the massive part, the number, type and place of horizons may be changed. next, we calculate the conserved and thermodynamic quantities and check the validation of the first law of thermodynamics. we also investigate thermal stability of these black holes in context of canonical ensemble. it will be shown that number, type and place of phase transition points are functions of different parameters which lead to dependency of stability conditions to these parameters. also, it will be shown how the behavior of temperature is modified due to extension of massive gravity and strong nonlinearity parameter. next, critical behavior of the system in extended phase space by considering cosmological constant as pressure is investigated. a study regarding neutral einstein-massive gravity in context of extended phase space is done. geometrical approach is employed to study the thermodynamical behavior of the system in context of heat capacity and extended phase space. it will be shown that gts, heat capacity and extended phase space have consistent results. finally, critical behavior of the system is investigated through use of another method. it will be pointed out that the results of this method is in agreement with other methods and follow the concepts of ordinary thermodynamics. | einstein-born-infeld-massive gravity: ads-black hole solutions and their thermodynamical properties |
we derive a novel four-dimensional black hole with planar horizon that asymptotes to the linear dilaton background. the usual growth of its entanglement entropy before page's time is established. after that, emergent islands modify to a large extent the entropy, which becomes finite and is saturated by its bekenstein-hawking value in accordance with the finiteness of the von neumann entropy of eternal black holes. we demonstrate that viewed from the string frame, our solution is the two-dimensional witten black hole with two additional free bosons. we generalize our findings by considering a general class of linear dilaton black hole solutions at a generic point along the σ-model renormalization group (rg) equations. for those, we observe that the entanglement entropy is "running" i.e. it is changing along the rg flow with respect to the two-dimensional worldsheet length scale. at any fixed moment before page's time the aforementioned entropy increases towards the infrared (ir) domain, whereas the presence of islands leads the running entropy to decrease towards the ir at later times. finally, we present a four-dimensional charged black hole that asymptotes to the linear dilaton background as well. we compute the associated entanglement entropy for the extremal case and we find that an island is needed in order for it to follow the page curve. | islands in linear dilaton black holes |
if the evaporation of a black hole formed from a pure state is unitary, the entanglement entropy of the hawking radiation should follow the page curve, increasing from zero until near the halfway point of the evaporation, and then decreasing back to zero. the general argument for the page curve is based on the assumption that the quantum state of the black hole plus radiation during the evaporation process is typical. in this paper, we show that the page curve can result from a simple dynamical input in the evolution of the black hole, based on a recently proposed signature of quantum chaos, without resorting to typicality. our argument is based on what we refer to as the "operator gas" approach, which allows one to understand the evolution of the microstate of the black hole from generic features of the heisenberg evolution of operators. one key feature which leads to the page curve is the possibility of dynamical processes where operators in the "gas" can "jump" outside the black hole, which we refer to as void formation processes. such processes are initially exponentially suppressed, but dominate after a certain time scale, which can be used as a dynamical definition of the page time. in the hayden-preskill protocol for young and old black holes, we show that void formation is also responsible for the transfer of information from the black hole to the radiation. we conjecture that void formation may provide a microscopic explanation for the recent semi-classical prescription of including islands in the calculation of the entanglement entropy of the radiation. | a dynamical mechanism for the page curve from quantum chaos |
we consider string theory on ads3× s3× 𝕋4 in the tensionless limit, with one unit of ns-ns flux. this theory is conjectured to describe the symmetric product orbifold cft. we consider the string on different euclidean backgrounds such as thermal ads3, the btz black hole, conical defects and wormhole geometries. in simple examples we compute the full string partition function. we find it to be independent of the precise bulk geometry, but only dependent on the geometry of the conformal boundary. for example, the string partition function on thermal ads3 and the conical defect with a torus boundary is shown to agree, thus giving evidence for the equivalence of the tensionless string on these different background geometries. we also find that thermal ads3 and the btz black hole are dual descriptions and the vacuum of the btz black hole is mapped to a single long string winding many times asymptotically around thermal ads3. thus the system yields a concrete example of the string-black hole transition. consequently, reproducing the boundary partition function does not require a sum over bulk geometries, but rather agrees with the string partition function on any bulk geometry with the appropriate boundary. we argue that the same mechanism can lead to a resolution of the factorization problem when geometries with disconnected boundaries are considered, since the connected and disconnected geometries give the same contribution and we do not have to include them separately. | partition functions of the tensionless string |
entanglement islands play an essential role in the recent breakthrough in addressing the black hole information paradox. inspired by double holography, it is conjectured that the entanglement islands can exist only in massive gravity. there are many pieces of evidence but also debates for this conjecture. this letter shows that the island rule works well for massless gravity in wedge holography with dgp terms on the brane. it helps to clarify the theoretical controversy and strongly indicates the universality of entanglement islands in gravity theories. | massless entanglement island in wedge holography |
it has been recently proposed by maldacena and qi that an eternal traversable wormhole in a two-dimensional anti-de sitter space is the gravity dual of the low temperature limit of two sachdev-ye-kitaev (syk) models coupled by a relevant interaction (which we will refer to as spin operator). we study spectral and eigenstate properties of this coupled syk model. we find that level statistics in the tail of the spectrum, and for a sufficiently weak coupling, show substantial deviations from random matrix theory, which suggests that traversable wormholes are not quantum chaotic. by contrast, for sufficiently strong coupling, corresponding to the black hole phase, level statistics are well described by random matrix theory. this transition in level statistics coincides approximately with a previously reported hawking-page transition for weak coupling. we show explicitly that this thermodynamic transition turns into a sharp crossover as the coupling increases. likewise, this critical coupling also corresponds to the one at which the overlap between the ground state and the thermofield double state (tfd) is smallest. in the range of sizes we can reach by exact diagonalization, the ground state is well approximated by the tfd only in the strong coupling limit. this is due to the fact that the ground state is close to the eigenstate of the spin operator corresponding to the lowest eigenvalue which is an exact tfd at infinite temperature. in this region, the spectral density is separated into blobs centered around the eigenvalues of the spin operator. for weaker couplings, the exponential decay of coefficients in a tensor product basis, typical of the tfd, becomes power law. finally, we also find that the total hamiltonian has an additional discrete symmetry which has not been reported previously. | quantum chaos transition in a two-site sachdev-ye-kitaev model dual to an eternal traversable wormhole |
qnms govern the linear response to perturbations of bhs, d-branes and fuzzballs and the gravitational wave signals in the ring-down phase of binary mergers. a remarkable connection between qnms of neutral bhs in 4d and quantum sw geometries describing the dynamics of n = 2 sym theories has been recently put forward. we extend the gauge/gravity dictionary to a large class of gravity backgrounds including charged and rotating bhs of einstein-maxwell theory in d = 4 , 5 dimensions, d3-branes, d1d5 'circular' fuzzballs and smooth horizonless geometries; all related to n = 2 sym with a single su (2) gauge group and fundamental matter. we find that photon-spheres, a common feature of all examples, are associated to degenerations of the classical elliptic sw geometry whereby a cycle pinches to zero size. quantum effects resolve the singular geometry and lead to a spectrum of quantized energies, labelled by the overtone number n. we compute the spectrum of qnms using exact wkb quantization, geodetic motion and numerical simulations and show excellent agreement between the three methods. we explicitly illustrate our findings for the case d3-brane qnms. | qnms of branes, bhs and fuzzballs from quantum sw geometries |
the vacuum entanglement entropy of maxwell theory, when evaluated by standard methods, contains an unexpected term with no known statistical interpretation. we resolve this two-decades old puzzle by showing that this term is the entanglement entropy of edge modes: classical solutions determined by the electric field normal to the entangling surface. we explain how the heat kernel regularization applied to this term leads to the negative divergent expression found by kabat. this calculation also resolves a recent puzzle concerning the logarithmic divergences of gauge fields in 3 +1 dimensions. | entanglement entropy of electromagnetic edge modes |
gauge-gravity duality is arguably our best hope for understanding quantum gravity. considerable progress has been made in relating scattering amplitudes in certain gravity theories to those in gauge theories — a correspondence dubbed the double copy. recently, double copies have also been realized in a classical setting, as maps between exact solutions of gauge theories and gravity. we present here a novel map between a certain class of real, exact solutions of einstein's equations and self-dual solutions of the flat-space vacuum maxwell equations. this map, which we call the newman-penrose map, is well-defined even for non-vacuum, non-stationary spacetimes, providing a systematic framework for exploring gravity solutions in the context of the double copy that have not been previously studied in this setting. to illustrate this, we present here the newman- penrose map for the schwarzschild and kerr black holes, and kinnersley's photon rocket. | the newman-penrose map and the classical double copy |
we exploit the recently proposed correspondence between gravitational perturbations and quantum seiberg-witten curves to compute the spectrum of quasi-normal modes of asymptotically flat kerr newman black holes and establish detailed gauge/gravity dictionaries for a large class of black holes, d-branes and fuzzballs in diverse dimensions. qnm frequencies obtained from the quantum periods of su(2) n = 2 sym with nf = 3 flavours are compared against numerical results, wkb (eikonal) approximation and geodetic motion showing remarkable agreement. starting from the master example relating quasi-normal modes of kerr-newman black holes in ads4 to su(2) gauge theory with nf = 4, we illustrate the procedure for some simple toy-models that allow analytic solutions. we also argue that the agt version of the gauge/gravity correspondence may give precious hints as to the physical/geometric origin of the quasi-normal modes/seiberg-witten connection and further elucidate interesting properties (such as tidal love numbers and grey-body factors) that can help discriminating black holes from fuzzballs. | more on the sw-qnm correspondence |
we construct the first example of a superstratum: a class of smooth horizonless supergravity solutions that are parameterized by arbitrary continuous functions of (at least) two variables and have the same charges as the supersymmetric d1-d5-p black hole. we work in type iib string theory on t 4 or k3 and our solutions involve a subset of fields that can be described by a six-dimensional supergravity with two tensor multiplets. the solutions can thus be constructed using a linear structure, and we give an explicit recipe to start from a superposition of modes specified by an arbitrary function of two variables and impose regularity to obtain the full horizonless solutions in closed form. we also give the precise cft description of these solutions and show that they are not dual to descendants of chiral primaries. they are thus much more general than all the known solutions whose cft dual is precisely understood. hence our construction represents a substantial step toward the ultimate goal of constructing the fully generic superstratum that can account for a finite fraction of the entropy of the three-charge black hole in the regime of parameters where the classical black hole solution exists. | habemus superstratum! a constructive proof of the existence of superstrata |
in this chapter we review the state-of-the-art of black holes in asymptotically safe gravity. after a brief recap of the asymptotic safety program, we shall summarize the features of asymptotic-safety-inspired black-hole models that have been constructed in the past by the so-called renormalization group improvement. specifically, we will discuss static configurations, both in spherically- and axially-symmetric settings, the role played by the cosmological constant, and the impact of the collapse dynamics in determining black-hole configurations realized in nature. in particular, we will review how quantum gravity could modify the buchdahl limit and the corresponding conditions to form ultra-compact objects and planckian black holes. we will then proceed by describing the most recent developments, particularly those aiming at making model building in asymptotic safety more rigorous and free from ambiguities. these include self-consistent and coordinate-independent versions of the renormalization group improvement, and next steps to fill the gap between model building and renormalization group computations in asymptotic safety. finally, we will focus on a selection of results that have been obtained from first-principle calculations or arguments, within and beyond asymptotic safety. concretely, we will review the state-of-the-art in determining black-hole entropy in asymptotic safety from a microstate counting, and progress in deriving the quantum-corrected newtonian potential. we will discuss how in quantum gravity theories linked to a gravitational path integral singularity resolution could be achieved by a dynamical suppression of singular configurations. finally, we will show that -- independent of the specific ultraviolet completion of gravity -- asymptotic modifications to schwarzschild black holes are strongly constrained by the principle of least action at large distance scales. | black holes in asymptotically safe gravity |
we provide an algorithm that shows how to decouple gravitational sources in pure lovelock gravity. this method allows to obtain several new and known analytic solutions of physical interest in scenarios with extra dimensions and with presence of higher curvature terms. furthermore, using our method, it is shown that applying the minimal geometric deformation to the anti de sitter space time it is possible to obtain regular black hole solutions. | a way of decoupling gravitational sources in pure lovelock gravity |
we view and provide further evidence for a number of swampland criteria, including the weak gravity conjecture, distance conjecture and bounds on the finiteness of the quantum gravity vacua from the prism of the finiteness of black hole entropy. furthermore we propose that at least all of these swampland statements may be more fundamentally a consequence of the finiteness of quantum gravity amplitudes. | finiteness and the swampland |
spin precession is one of the key physical effects that coul unveil the origin of the compact binaries detected by ground- and space-based gravitational-wave (gw) detectors, and shed light on their possible formation channels. efficiently and accurately modeling the gw signals emitted by these systems is crucial to extract their properties. here, we present seobnrv5phm, a multipolar precessing-spin waveform model within the effective-one-body formalism for the full signal (i.e. inspiral, merger and ringdown) of binary black holes (bbhs). in the nonprecessing limit, the model reduces to seobnrv5hm, which is calibrated to 442 numerical-relativity (nr) simulations, 13 waveforms from bh perturbation theory, and nonspinning energy flux from second-order gravitational self-force theory. we remark that seobnrv5phm is not calibrated to precessing-spin nr waveforms from the simulating extreme spacetimes collaboration. we validate seobnrv5phm by computing the unfaithfulness against 1543 precessing-spin nr waveforms, and find that for 99.8% (84.4%) of the cases, the maximum value, in the total mass range 20 - 300 m⊙ , is below 3% (1%). these numbers reduce to 95.3% (60.8%) when using the previous version of the seobnr family, seobnrv4phm, and to 78.2% (38.3%) when using the state-of-the-art frequency-domain multipolar precessing-spin phenomenological imrphenomxphm model. due to much better computational efficiency of seobnrv5phm compared to seobnrv4phm, we are also able to perform extensive bayesian parameter estimation on synthetic signals and gw events observed by ligo-virgo detectors. we show that seobnrv5phm can be used as a standard tool for inference analyses to extract astrophysical and cosmological information of large catalogs of bbhs. | next generation of accurate and efficient multipolar precessing-spin effective-one-body waveforms for binary black holes |
the phenomenon of spontaneous scalarisation of charged black holes (bhs) has recently motivated studies of various einstein-maxwell-scalar models. within these models, different classes of bh solutions are possible, depending on the non-minimal coupling function f (ϕ), between the scalar field and the maxwell invariant. here we consider the class wherein both the (bald) electrovacuum reissner-nordström (rn) bh and new scalarised bhs co-exist, and the former are never unstable against scalar perturbations. in particular we examine the model, within this subclass, with a quartic coupling function: f (φ) = 1 + αφ4. the domain of existence of the scalarised bhs, for fixed α, is composed of two branches. the first branch (cold scalarised bhs) is continuously connected to the extremal rn bh. the second branch (hot scalarised bhs) connects to the first one at the minimum value of the charge to mass ratio and it includes overcharged bhs. we then assess the perturbative stability of the scalarised solutions, focusing on spherical perturbations. on the one hand, cold scalarised bhs are shown to be unstable by explicitly computing growing modes. the instability is quenched at both endpoints of the first branch. on the other hand, hot scalarised bhs are shown to be stable by using the s-deformation method. thus, in the spherical sector this model possesses two stable bh local ground states (rn and hot scalarised). we point out that the branch structure of bhs in this model parallels the one of bhs in five dimensional vacuum gravity, with [myers-perry bhs, fat rings, thin rings] playing the role of [rn, cold scalarised, hot scalarised] bhs. | einstein-maxwell-scalar black holes: the hot, the cold and the bald |
the distribution of effective spin χeff, a parameter that encodes the degree of spin-orbit alignment in a binary system, has been widely regarded as a robust discriminator between the isolated and dynamical formation pathways for merging binary black holes. until the recent release of the gwtc-2 catalog, such tests have yielded inconclusive results due to the small number of events with measurable nonzero spins. in this work, we study the χeff distribution of the binary black holes detected in the ligo-virgo o1-o3a observing runs. our focus is on the degree to which the χeff distribution is symmetric about χeff=0 and whether the data provide support for a population of negative-χeff systems. we find that the χeff distribution is asymmetric at 95% credibility, with an excess of aligned-spin binary systems (χeff>0 ) over antialigned ones. moreover, we find that there is no evidence for negative-χeff systems in the current population of binary black holes. thus, based solely on the χeff distribution, dynamical formation is disfavored as being responsible for the entirety of the observed merging binary black holes, while isolated formation remains viable. we also study the mass distribution of the current binary black hole population, confirming that a single truncated power-law distribution in the primary source-frame mass, m1 s, fails to describe the observations. instead, we find that the preferred models have a steep feature at m1 s∼40 m⊙ consistent with a step and an extended, shallow tail to high masses. | distribution of effective spins and masses of binary black holes from the ligo and virgo o1-o3a observing runs |
we present new results on the equation of state and transition line of hot and dense strongly interacting qcd matter, obtained from a bottom-up einstein-maxwell-dilaton holographic model. we considerably expand the previous coverage in baryon densities in this model by implementing new numerical methods to map the holographic black hole solutions onto the qcd phase diagram. we are also able to obtain, for the first time, the first-order phase transition line in a wide region of the phase diagram. comparisons with the most recent lattice results for the qcd thermodynamics are also presented. | hot and dense quark-gluon plasma thermodynamics from holographic black holes |
observables related to the real part of the gravitational eikonal, such as the deflection angle and time delay, have been found so far to have a smooth post-minkowskian (pm) expansion whose validity extends from the non-relativistic to the most extreme ultra-relativistic (ur) regime, which smoothly connects with massless particle collisions. to describe gravitational radiation, the eikonal phase has to be promoted to a unitary operator for which we motivate a proposal and start discussing properties in the soft-radiation limit. a convergent pm expansion is found to only hold below an ur bound (discussed in the gr literature in the seventies) above which a different expansion is instead needed implying, in general, some non-analyticity in newton's constant. in this extreme ur regime soft radiative observables receive contributions only from gravitons and are therefore universal. this generalises the pattern discussed in [1] beyond the elastic case. | the eikonal operator at arbitrary velocities i: the soft-radiation limit |
canonical quantization is often used to suggest new effects in quantum gravity, in the dynamics as well as the structure of space-time. usually, possible phenomena are first seen in a modified version of the classical dynamics, for instance in an effective friedmann equation, but there should also be implications for a modified space-time structure. quantum space-time effects, however, are often ignored in this setting because they are not obvious: they require a careful analysis of gauge transformations and the anomaly problem. it is shown here how modified space-time structures and effective line elements can be derived unambiguously, provided an off-shell anomaly-free system of modified constraints exists. the resulting effective line elements reveal signature change as an inescapable consequence of nonclassical gauge transformations in the presence of holonomy modifications. the general framework is then specialized to black-hole models in loop quantum gravity. in contrast to previous studies, a self-consistent space-time structure is taken into account, leading to a new picture of black-hole interiors. | effective line elements and black-hole models in canonical loop quantum gravity |
motivated by recent studies of the information paradox in (1+1)-d anti-de sitter spacetime with a bath described by a (1+1)-d conformal field theory, we study the dynamics of second ŕenyi entropy of the sachdev-ye-kitaev (syk) model (χ) coupled to a majorana chain bath (ψ). the system is prepared in the thermofield double (tfd) state and then evolved by hl + hr. for small system-bath coupling, we find that the second rényi entropy sχl ,χ r (2 ) of the syk model undergoes a first order transition during the evolution. in the sense of holographic duality, the long-time solution corresponds to a "replica wormhole". the transition time corresponds to the page time of a black hole coupled to a thermal bath. we further study the information scrambling and retrieval by introducing a classical control bit, which controls whether or not we add a perturbation in the syk system. the mutual information between the bath and the control bit shows a positive jump at the page time, indicating that the entanglement wedge of the bath includes an island in the holographic bulk. | replica wormhole and information retrieval in the syk model coupled to majorana chains |
we study the thermal diffusivity dt in models of metals without quasiparticle excitations ("strange metals"). the many-body quantum chaos and transport properties of such metals can be efficiently described by a holographic representation in a gravitational theory in an emergent curved spacetime with an additional spatial dimension. we find that at generic infrared fixed points dt is always related to parameters characterizing many-body quantum chaos: the butterfly velocity vb and lyapunov time τl through dt∼vb2τl. the relationship holds independently of the charge density, periodic potential strength, or magnetic field at the fixed point. the generality of this result follows from the observation that the thermal conductivity of strange metals depends only on the metric near the horizon of a black hole in the emergent spacetime and is otherwise insensitive to the profile of any matter fields. | thermal diffusivity and chaos in metals without quasiparticles |
we present a first-principles cft calculation corresponding to the spherical collapse of a shell of matter in three dimensional quantum gravity. in field theory terms, we describe the equilibration process, from early times to thermalization, of a cft following a sudden injection of energy at time t = 0. by formulating a continuum version of zamolodchikov's monodromy method to calculate conformal blocks at large central charge c, we give a framework to compute a general class of probe observables in the collapse state, incorporating the full backreaction of matter fields on the dual geometry. this is illustrated by calculating a scalar field two-point function at time-like separation and the time-dependent entanglement entropy of an interval, both showing thermalization at late times. the results are in perfect agreement with previous gravity calculations in the ads3-vaidya geometry. information loss appears in the cft as an explicit violation of unitarity in the 1 /c expansion, restored by nonperturbative corrections. | black hole collapse in the 1 /c expansion |
one of the major aims of gravitational wave astronomy is to observationally test the kerr nature of black holes. the strongest such test, with minimal additional assumptions, is provided by observations of multiple ringdown modes, also known as black hole spectroscopy. for the gravitational wave merger event gw190521, we have previously claimed the detection of two ringdown modes emitted by the remnant black hole. in this paper we provide further evidence for the detection of multiple ringdown modes from this event. we analyse the recovery of simulated gravitational wave signals designed to replicate the ringdown properties of gw190521. we quantify how often our detection statistic reports strong evidence for a sub-dominant $(\ell,m,n)=(3,3,0)$ ringdown mode, even when no such mode is present in the simulated signal. we find this only occurs with a probability $\sim 0.02$, which is consistent with a bayes factor of $56 \pm 1$ (1$\sigma$ uncertainty) found for gw190521. we also quantify our agnostic analysis of gw190521, in which no relationship is assumed between ringdown modes, and find that only 1 in 250 simulated signals without a $(3,3,0)$ mode yields a result as significant as gw190521. conversely, we verify that when simulated signals do have an observable $(3,3,0)$ mode they consistently yield a strong evidence and significant agnostic results. we also find that constraints on deviations from the $(3,3,0)$ mode on gw190521-like signals with a $(3,3,0)$ mode are consistent with what was obtained from our previous analysis of gw190521. our results strongly support our previous conclusion that the gravitational wave signal from gw190521 contains an observable sub-dominant $(\ell,m,n)=(3,3,0)$ mode. | statistical validation of the detection of a sub-dominant quasi-normal mode in gw190521 |
it has been suggested in recent work that the page curve of hawking radiation can be recovered using computations in semi-classical gravity provided one allows for "islands" in the gravity region of quantum systems coupled to gravity. the explicit computations so far have been restricted to black holes in two-dimensional jackiw-teitelboim gravity. in this note, we numerically construct a five-dimensional asymptotically ads geometry whose boundary realizes a four-dimensional hartle-hawking state on an eternal ads black hole in equilibrium with a bath. we also numerically find two types of extremal surfaces: ones that correspond to having or not having an island. the version of the information paradox involving the eternal black hole exists in this setup, and it is avoided by the presence of islands. thus, recent computations exhibiting islands in two-dimensional gravity generalize to higher dimensions as well. | entanglement islands in higher dimensions |
we show that complementary state-specific reconstruction of logical (bulk) operators is equivalent to the existence of a quantum minimal surface prescription for physical (boundary) entropies. this significantly generalizes both sides of an equivalence previously shown by harlow[1]; in particular, we do not require the entanglement wedge to be the same for all states in the code space. in developing this theorem, we construct an emergent bulk geometry for general quantum codes, defining ``areas'' associated to arbitrary logical subsystems, and argue that this definition is ``functionally unique.'' we also formalize a definition of bulk reconstruction that we call ``state-specific product unitary'' reconstruction. this definition captures the quantum error correction (qec) properties present in holographic codes and has potential independent interest as a very broad generalization of qec; it includes most traditional versions of qec as special cases. our results extend to approximate codes, and even to the ``non-isometric codes'' that seem to describe the interior of a black hole at late times. | quantum minimal surfaces from quantum error correction |
large black holes in anti-de sitter space have positive specific heat and do not evaporate. in order to mimic the behavior of evaporating black holes, one may couple the system to an external bath. in this paper we explore a rich family of such models, namely ones obtained by coupling two holographic cfts along a shared interface (icfts). we focus on the limit where the bulk solution is characterized by a thin brane separating the two individual duals. these systems may be interpreted in a double holographic way, where one integrates out the bath and ends up with a lower-dimensional gravitational braneworld dual to the interface degrees of freedom. our setup has the advantage that all observables can be defined and calculated by only relying on standard rules of ads/cft. we exploit this to establish a number of general results, relying on a detailed analysis of the geodesics in the bulk. firstly, we prove that the entropy of hawking radiation in the braneworld is obtained by extremizing the generalized entropy, and moreover that at late times a so-called `island saddle' gives the dominant contribution. we also derive takayanagi's prescription for calculating entanglement entropies in bcfts as a limit of our icft results. | sailing past the end of the world and discovering the island |
we develop a number of novel "black-bounce" spacetimes. these are specific regular black holes where the area radius always remains nonzero, thereby leading to a "throat" that is either timelike (corresponding to a traversable wormhole), spacelike (corresponding to a "bounce" into a future universe), or null (corresponding to a "one-way wormhole"). we first perform a general analysis of the regularity conditions for such a spacetime and then consider a number of specific examples. the examples are constructed using a mass function similar to that of fan-wang and fall into several particular cases, such as the original simpson-visser model, a bardeen-type model, and other generalizations thereof. we analyze the regularity, energy conditions, and causal structure of these models. the main results are several new geometries, more complex than before, with two or more horizons, with the possibility of an extremal case. we derive a general theorem regarding static spacetime regularity and another general theorem regarding (non)satisfaction of the classical energy conditions. | novel black-bounce spacetimes: wormholes, regularity, energy conditions, and causal structure |
we consider the action principles that are the lower dimensional limits of the einstein-gauss-bonnet gravity via the kaluza-klein route. we study the vacua and obtain some exact solutions. we find that the reality condition of the theories may select one vacuum over the other from the two vacua that typically arise in einstein-gauss-bonnet gravity. we obtain exact black hole and cosmological solutions carrying scalar hair, including scalar hairy btz black holes with both mass and angular momentum turned on. we also discuss the holographic central charges in the asymptotic ads backgrounds. | vacua and exact solutions in lower-d limits of egb |
we use the notion of double holography to study hawking radiation emitted by the eternal btz black hole in equilibrium with a thermal bath, but in the form of warped cft2 degrees of freedom. in agreement with the literature, we find entanglement islands and a phase transition in the entanglement surface, but our results differ significantly from work in ads/cft in three major ways: (1) the late-time entropy decreases in time, (2) island degrees of freedom exist at all times, not just at late times, with the phase transition changing whether or not these degrees of freedom include the black hole interior, and (3) the physics involves a field-theoretic ir divergence emerging when the boundary interval is too big relative to the black hole's inverse temperature. this behavior in the entropy appears to be consistent with the non-unitarity of holographic warped cft2 and demonstrates that the islands are not a phenomenon restricted to black hole information in unitary setups. | warped information and entanglement islands in ads/wcft |
we construct perturbative classical solutions of the yang-mills equations coupled to dynamical point particles carrying color charge. by applying a set of color to kinematics replacement rules first introduced by bern, carrasco and johansson, these are shown to generate solutions of d -dimensional dilaton gravity, which we also explicitly construct. agreement between the gravity result and the gauge theory double copy implies a correspondence between non-abelian particles and gravitating sources with dilaton charge. when the color sources are highly relativistic, dilaton exchange decouples, and the solutions we obtain match those of pure gravity. we comment on possible implications of our findings to the calculation of gravitational waveforms in astrophysical black hole collisions, directly from computationally simpler gluon radiation in yang-mills theory. | radiation and the classical double copy for color charges |
we show that in $\text{o}(d)$ invariant matrix theories containing a large number $d$ of complex or hermitian matrices, one can define a $d\rightarrow\infty$ limit for which the sum over planar diagrams truncates to a tractable, yet non-trivial, sum over melon diagrams. in particular, results obtained recently in syk and tensor models can be generalized to traditional, string-inspired matrix quantum mechanical models of black holes. | the large d limit of planar diagrams |
we find hydrodynamic behavior in large simply spinning five-dimensional anti-de sitter black holes. these are dual to spinning quantum fluids through the ads/cft correspondence constructed from string theory. due to the spatial anisotropy introduced by the angular momentum, hydrodynamic transport coefficients are split into groups longitudinal or transverse to the angular momentum, and aligned or anti-aligned with it. analytic expressions are provided for the two shear viscosities, the longitudinal momentum diffusion coefficient, two speeds of sound, and two sound attenuation coefficients. known relations between these coefficients are generalized to include dependence on angular momentum. the shear viscosity to entropy density ratio varies between zero and 1/(4π) depending on the direction of the shear. these results can be applied to heavy ion collisions, in which the most vortical fluid was reported recently. in passing, we show that large simply spinning five-dimensional myers-perry black holes are perturbatively stable for all angular momenta below extremality. | hydrodynamics of simply spinning black holes & hydrodynamics for spinning quantum fluids |
we obtain an asymptotic formula for the average value of the operator product expansion coefficients of any unitary, compact two dimensional cft with c > 1. this formula is valid when one or more of the operators has large dimension or — in the presence of a twist gap — has large spin. our formula is universal in the sense that it depends only on the central charge and not on any other details of the theory. this result unifies all previous asymptotic formulas for cft2 structure constants, including those derived from crossing symmetry of four point functions, modular covariance of torus correlation functions, and higher genus modular invariance. we determine this formula at finite central charge by deriving crossing kernels for higher genus crossing equations, which give analytic control over the structure constants even in the absence of exact knowledge of the conformal blocks. the higher genus modular kernels are obtained by sewing together the elementary kernels for four-point crossing and modular transforms of torus one-point functions. our asymptotic formula is related to the dozz formula for the structure constants of liouville theory, and makes precise the sense in which liouville theory governs the universal dynamics of heavy operators in any cft. the large central charge limit provides a link with 3d gravity, where the averaging over heavy states corresponds to a coarse-graining over black hole microstates in holographic theories. our formula also provides an improved understanding of the eigenstate thermalization hypothesis (eth) in cft2, and suggests that eth can be generalized to other kinematic regimes in two dimensional cfts. | universal dynamics of heavy operators in cft2 |
black hole solutions in general relativity come with pathologies such as singularity and mass inflation instability, which are believed to be cured by a yet-to-be-found quantum theory of gravity. without such consistent description, one may model theory-agnostic phenomenological black holes that bypass the aforesaid issues. these so-called regular black holes are extensively studied in the literature using parameterized modifications over the black hole solutions of general relativity. however, since there exist several ways to model such black holes, it is important to study the consistency and viability of these solutions from both theoretical and observational perspectives. in this work, we consider a recently proposed model of regularized stable rotating black holes having two extra parameters in addition to the mass and spin of a kerr solution. we start by computing their quasi-normal modes under scalar perturbation and investigate the impact of those additional parameters on black hole stability. in the second part, we study shadows of the central compact objects in m 87∗ and s g r a∗ modelled by these regularized black holes and obtain stringent bounds on the parameter space requiring consistency with event horizon telescope observations. | regularized stable kerr black hole: cosmic censorships, shadow and quasi-normal modes |
we study some aspects of the de sitter version of jackiw-teitelboim gravity. though we do not have propagating gravitons, we have a boundary mode when we compute observables with a fixed dilaton and metric at the boundary. we compute the no-boundary wavefunctions and probability measures to all orders in perturbation theory. we also discuss contributions from different topologies, borrowing recent results by saad, shenker and stanford. we discuss how the boundary mode leads to gravitational corrections to cosmological observables when we add matter. finally, starting from a four dimensional gravity theory with a positive cosmological constant, we consider a nearly extremal black hole and argue that some observables are dominated by the two dimensional nearly de sitter gravity dynamics. | two dimensional nearly de sitter gravity |
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