abstract stringlengths 3 192k | title stringlengths 4 857 |
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we examine recent claims that evidence for an overtone in the ringdown of the gw150914 binary black hole merger was a result of noise anomalies. we cannot reproduce these claims, finding that our previous analysis of this event is robust to data analysis choices and consistent with the expectation that strain after the peak is well described as a superposition of quasinormal modes of the remnant black hole. we discuss the meaning and implications of establishing that any specific ringdown mode was detected, and argue that it is misguided to expect actual ligo-virgo data to inform the discussion of whether or why the merger looks linear. | revisiting the ringdown of gw150914 |
we compute the far-field time-domain waveform of the gravitational waves produced in the scattering of two spinning massive objects. the results include linear-in-spin ($s$) couplings and first-order gravitational corrections ($g^3$), and are valid for encounters in the weak-field regime. employing a field-theory framework based on the scattering of massive scalar and vector particles coupled to einstein-hilbert gravity, we derive results for leading and the next-to-leading spectral waveforms. we provide analytic expressions for the required scattering data, which include trees, one-loop amplitudes and their cuts. the expressions are extracted from numerical amplitude evaluations with the caravel program, using analytic reconstruction techniques applied in the classical limit. we confirm a recent prediction for infrared physics of the classical observable, and observe the surprising appearance of a ultraviolet singularity, which drops out in the far-field waveform. | gravitational bremsstrahlung in black-hole scattering at $\\mathcal{o}(g^3)$: linear-in-spin effects |
in the generalized off-shell free energy landscape, black holes can be treated as thermodynamic topological defects. the local topological properties of the spacetime can be reflected by the winding numbers at the defects, while the global topological nature can be classified by the topological number which is the sum of all local winding numbers. we propose that the winding numbers can be calculated via the residues of isolated one-order pole points of characterized functions constructed from the off-shell free energy. using the residue method, we show that the topologies of black holes can be divided into three classes with the topological numbers being -1, 0, and 1, respectively, being consistent with the results obtained in [phys. rev. lett. 129, 191101 (2022)] by using the topological current method. moreover, we point out that standard defect points, generation and annihilation points, and critical points can be distinguished by coefficients of the laurent series of the off-shell characterized function at those singular points. | revisiting thermodynamic topologies of black holes |
it was recently shown that the von neumann algebras of observables dressed to the mass of a schwarzschild-ads black hole or an observer in de sitter are type ii, and thus admit well-defined traces. the von neumann entropies of "semi-classical" states were found to be generalized entropies. however, these arguments relied on the existence of an equilibrium (kms) state and thus do not apply to, e.g., black holes formed from gravitational collapse, kerr black holes, or black holes in asymptotically de sitter space. in this paper, we present a general framework for obtaining the algebra of dressed observables for linear fields on any spacetime with a killing horizon. we prove, assuming the existence of a stationary (but not necessarily kms) state and suitable decay of solutions, a structure theorem that the algebra of dressed observables always contains a type ii factor "localized" on the horizon. these assumptions have been rigorously proven in most cases of interest. applied to the algebra in the exterior of an asymptotically flat kerr black hole, where the fields are dressed to the black hole mass and angular momentum, we find a product of a type ii$_{\infty}$ algebra on the horizon and a type i$_{\infty}$ algebra at past null infinity. in schwarzschild-de sitter, despite the fact that we introduce an observer, the quantum field observables are dressed to the perturbed areas of the black hole and cosmological horizons and is the product of type ii$_{\infty}$ algebras on each horizon. in all cases, the von neumann entropy for semiclassical states is given by the generalized entropy. our results suggest that in all cases where there exists another "boundary structure" (e.g., an asymptotic boundary or another killing horizon) the algebra of observables is type ii$_{\infty}$ and in the absence of such structures (e.g., de sitter) the algebra is type ii$_{1}$. | generalized black hole entropy is von neumann entropy |
in this second part of the study initiated in [1], we investigate holographic complexity for eternal black hole backgrounds perturbed by shock waves, with both the complexity=action (ca) and complexity=volume (cv) proposals. in particular, we consider vaidya geometries describing a thin shell of null fluid with arbitrary energy falling in from one of the boundaries of a two-sided ads-schwarzschild spacetime. we demonstrate how known properties of complexity, such as the switchback effect for light shocks, as well as analogous properties for heavy ones, are imprinted in the complexity of formation and in the full time evolution of complexity. following our discussion in [1], we find that in order to obtain the expected properties of the complexity, the inclusion of a particular counterterm on the null boundaries of the wheeler-dewitt patch is required for the ca proposal. | holographic complexity in vaidya spacetimes. part ii |
the double copy relates scattering amplitudes in gauge and gravity theories. in this paper, we expand the scope of the double copy to construct spacetime metrics through a systematic perturbative expansion. the perturbative procedure is based on direct calculation in yang-mills theory, followed by squaring the numerator of certain perturbative diagrams as specified by the double-copy algorithm. the simplest spherically symmetric, stationary spacetime from the point of view of this procedure is a particular member of the janis-newman-winicour family of naked singularities. our work paves the way for applications of the double copy to physically interesting problems such as perturbative black-hole scattering. | perturbative spacetimes from yang-mills theory |
we initiate a series of works where we study the interior of dynamical rotating vacuum black holes without symmetry. in the present paper, we take up the problem starting from appropriate cauchy data for the einstein vacuum equations defined on a hypersurface already within the black hole interior, representing the expected geometry just inside the event horizon. we prove that for all such data, the maximal cauchy evolution can be extended across a non-trivial piece of cauchy horizon as a lorentzian manifold with continuous metric. in subsequent work, we will retrieve our assumptions on data assuming only that the black hole event horizon geometry suitably asymptotes to a rotating kerr solution. in particular, if the exterior region of the kerr family is proven to be dynamically stable---as is widely expected---then it will follow that the $c^0$-inextendibility formulation of penrose's celebrated strong cosmic censorship conjecture is in fact false. the proof suggests, however, that the $c^0$-metric cauchy horizons thus arising are generically singular in an essential way, representing so-called "weak null singularities", and thus that a revised version of strong cosmic censorship holds. | the interior of dynamical vacuum black holes i: the $c^0$-stability of the kerr cauchy horizon |
we present the imrphenomxhm frequency domain phenomenological waveform model for the inspiral, merger, and ringdown of quasicircular nonprecessing black hole binaries. the model extends the imrphenomxas waveform model [g. pratten, s. husa, c. garcía-quirós, m. colleoni, a. ramos-buades, h. estellés, and r. jaume, preceding paper, phys. rev. d 102, 064001 (2020), 10.1103/physrevd.102.064001], which describes the dominant quadrupole modes ℓ=|m |=2 , to the harmonics (ℓ,|m |)=(2 ,1 ),(3 ,3 ),(3 ,2 ),(4 ,4 ), and includes mode mixing effects for the (3,2) spherical harmonic. imrphenomxhm is calibrated against hybrid waveforms, which match an inspiral phase described by the effective-one-body model and post-newtonian amplitudes for the subdominant harmonics to numerical relativity waveforms and numerical solutions to the perturbative teukolsky equation for large mass ratios up to 1000. | multimode frequency-domain model for the gravitational wave signal from nonprecessing black-hole binaries |
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 |
following previous work of ours in spherical symmetry, we here propose a new parametric framework to describe the spacetime of axisymmetric black holes in generic metric theories of gravity. in this case, the metric components are functions of both the radial and the polar angular coordinates, forcing a double expansion to obtain a generic axisymmetric metric expression. in particular, we use a continued-fraction expansion in terms of a compactified radial coordinate to express the radial dependence, while we exploit a taylor expansion in terms of the cosine of the polar angle for the polar dependence. these choices lead to a superior convergence in the radial direction and to an exact limit on the equatorial plane. as a validation of our approach, we build parametrized representations of kerr, rotating dilaton, and einstein-dilaton-gauss-bonnet black holes. the match is already very good at lowest order in the expansion and improves as new orders are added. we expect a similar behavior for any stationary and axisymmetric black-hole metric. | general parametrization of axisymmetric black holes in metric theories of gravity |
we study the p -v criticality and phase transition in the extended phase space of charged anti-de sitter black holes in canonical ensemble of ghost-free massive gravity, where the cosmological constant is viewed as a dynamical pressure of the black hole system. we give the generalized thermodynamic first law and the smarr relation with massive gravity correction. we find that not only when the horizon topology is spherical but also in the ricci flat or hyperbolic case, there appear the p -v criticality and phase transition up to the combination k +c02c2m2 in the four-dimensional case, where k characterizes the horizon curvature and c2m2 is the coefficient of the second term of massive potential associated with the graviton mass. the positivity of such combination indicate the van der waals-like phase transition. when the spacetime dimension is larger then four, the maxwell charge there seems unnecessary for the appearance of critical behavior, but a infinite repulsion effect needed, which can also be realized through negative valued c3m2 or c4m2 , which is third or fourth term of massive potential. when c3m2 is positive, a hawking-page-like black hole to vacuum phase transition is shown in the five-dimensional chargeless case. for the van der waals-like phase transition in four and five spacetime dimensions, we calculate the critical exponents near the critical point and find they are the same as those in the van der waals liquid-gas system. | p -v criticality in the extended phase space of black holes in massive gravity |
we review potential low-frequency gravitational-wave sources, which are expected to be detected by taiji, a chinese space-based gravitational-wave detector, estimate the detection rates of these gravitational-wave sources and present the parameter estimation of massive black hole binaries. | taiji program: gravitational-wave sources |
the theory of hawking radiation can be tested in laboratory analogues of black holes. we use light pulses in nonlinear fiber optics to establish artificial event horizons. each pulse generates a moving perturbation of the refractive index via the kerr effect. probe light perceives this as an event horizon when its group velocity, slowed down by the perturbation, matches the speed of the pulse. we have observed in our experiment that the probe stimulates hawking radiation, which occurs in a regime of extreme nonlinear fiber optics where positive and negative frequencies mix. | observation of stimulated hawking radiation in an optical analogue |
on september 14, 2015, at 09∶50:45 utc the two detectors of the laser interferometer gravitational-wave observatory (ligo) simultaneously observed the binary black hole merger gw150914. we report the results of a matched-filter search using relativistic models of compact-object binaries that recovered gw150914 as the most significant event during the coincident observations between the two ligo detectors from september 12 to october 20, 2015 gw150914 was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203000 years, equivalent to a significance greater than 5.1 σ . | gw150914: first results from the search for binary black hole coalescence with advanced ligo |
we study the shadows of the fully non-linear, asymptotically flat einstein-dilaton-gauss-bonnet (edgb) black holes (bhs), for both static and rotating solutions. we find that, in all cases, these shadows are smaller than for comparable kerr bhs, i.e. with the same total mass and angular momentum under similar observation conditions. in order to compare both cases we provide quantitative shadow parameters, observing in particular that the differences in the shadows mean radii are never larger than the percent level. therefore, generically, edgb bhs cannot be excluded by (near future) shadow observations alone. on the theoretical side, we find no clear signature of some exotic features of edgb bhs on the corresponding shadows, such as the regions of negative (komar, say) energy density outside the horizon. we speculate that this is due to the fact that the komar energy interior to the light rings (or more precisely, the surfaces of constant radial coordinate that intersect the light rings in the equatorial plane) is always smaller than the adm mass, and consequently the corresponding shadows are smaller than those of comparable kerr bhs. the analysis herein provides a clear example that it is the light ring impact parameter, rather than its ;size;, that determines a bh shadow. | shadows of einstein-dilaton-gauss-bonnet black holes |
the central dogma of black hole physics — which says that from the outside a black hole can be described in terms of a quantum system with exp(area/4gn) states evolving unitarily — has recently been supported by computations indicating that the interior of the black hole is encoded in the hawking radiation of the exterior. in this paper, we probe whether such a dogma for cosmological horizons has any support from similar computations. the fact that the de sitter bifurcation surface is a minimax surface (instead of a maximin surface) causes problems with this interpretation when trying to import calculations analogous to the ads case. this suggests anchoring extremal surfaces to the horizon itself, where we formulate a two-sided extremization prescription and find answers consistent with general expectations for a quantum theory of de sitter space: vanishing total entropy, an entropy of a/4gn when restricting to a single static patch, an entropy of a subregion of the horizon which grows as the region size grows until an island-like transition at half the horizon size when the entanglement wedge becomes the entire static patch interior, and a de sitter version of the hartman-maldacena transition. | the central dogma and cosmological horizons |
in this note we study the 1 + 1 dimensional jackiw-teitelboim gravity in lorentzian signature, explicitly constructing the gauge-invariant classical phase space and the quantum hilbert space and hamiltonian. we also semiclassically compute the hartle-hawking wave function in two different bases of this hilbert space. we then use these results to illustrate the gravitational version of the factorization problem of ads/cft: the hilbert space of the two-boundary system tensor-factorizes on the cft side, which appears to be in tension with the existence of gauge constraints in the bulk. in this model the tension is acute: we argue that jt gravity is a sensible quantum theory, based on a well-defined lorentzian bulk path integral, which has no cft dual. in bulk language, it has wormholes but it does not have black hole microstates. it does however give some hint as to what could be added to rectify these issues, and we give an example of how this works using the syk model. finally we suggest that similar comments should apply to pure einstein gravity in 2 + 1 dimensions, which we'd then conclude also cannot have a cft dual, consistent with the results of maloney and witten. | the factorization problem in jackiw-teitelboim gravity |
the black-hole information paradox provides one of the sharpest foci for the conflict between quantum mechanics and general relativity and has become the proving-ground of would-be theories of quantum gravity. string theory has made significant progress in resolving this paradox, and has led to the fuzzball and microstate geometry programs. the core principle of these programs is that horizons and singularities only arise if one tries to describe gravity using a theory that has too few degrees of freedom to resolve the physics. string theory has sufficiently many degrees of freedom and this naturally leads to fuzzballs and microstate geometries: the reformation of black holes into objects with neither horizons nor singularities. this not only resolves the paradox but provides new insights into the microstructure of black holes. we summarize the current status of this approach and describe future prospects and additional insights that are now within reach. this paper is an expanded version of our snowmass white paper arxiv:2203.04981. | fuzzballs and microstate geometries: black-hole structure in string theory |
we revisit the confinement/deconfinement transition in n = 4 super yang-mills (sym) theory and its relation to the hawking-page transition in gravity. recently there has been substantial progress on counting the microstates of 1/16-bps extremal black holes. however, there is presently a mismatch between the hawking-page transition and its avatar in n = 4 sym. this led to speculations about the existence of new gravitational saddles that would resolve the mismatch. here we exhibit a phenomenon in complex matrix models which we call "delayed deconfinement." it turns out that when the action is complex, due to destructive interference, tachyonic modes do not necessarily condense. we demonstrate this phenomenon in ordinary integrals, a simple unitary matrix model, and finally in the context of n = 4 sym. delayed deconfinement implies a first-order transition, in contrast to the more familiar cases of higher-order transitions in unitary matrix models. we determine the deconfinement line and find remarkable agreement with the prediction of gravity. on the way, we derive some results about the gross-witten-wadia model with complex couplings. our techniques apply to a wide variety of (susy and non-susy) gauge theories though in this paper we only discuss the case of n = 4 sym. | delayed deconfinement and the hawking-page transition |
by combining the ads/bcft correspondence and the brane world holography, we expect an equivalence relation between a boundary conformal field theory (bcft) and a gravitational system coupled to a cft. however, it still remains unclear how the boundary condition of the bcft is translated in the gravitational system. we examine this duality relation in a two-dimensional setup by looking at the computation of entanglement entropy and energy flux conservation. we also identify the two-dimensional gravity which is dual to the boundary dynamics of a bcft. moreover, we show that by considering a gravity solution with scalar fields turned on, we can reproduce one point functions correctly in the ads/bcft. | bcft and islands in two dimensions |
we systematically calculate the quantum extremal surface (qes) associated with hawking radiation for general d-dimensional (d ≥ 2) asymptotically flat (or ads) eternal black holes using the island formula. we collect the hawking radiation particles by a non-gravitational bath and find that a qes exists in the near-horizon region outside the black hole when c . g(d) is smaller enough where c is the central charge of the conformal matter and g(d) the d-dimensional newton constant. the locations of the qes in these backgrounds are obtained and the late-time radiation entropy saturates the two times of black hole entropy. finally, we numerically check that the no island configuration exists once c . g(d) exceeds a certain upper bound in two-dimensional generalized dilaton theories (gdt). when c . g(d) close to the upper bound, the backreaction of the matter field on the background can not be neglected. we also consider the conditions of existence of the island configuration with the backreaction and prove that the upper bound also exist for the witten black hole and weyl-related witten black hole. | the universality of islands outside the horizon |
in an ordinary quantum field theory, the 'split property' implies that the state of the system can be specified independently on a bounded subregion of a cauchy slice and its complement. this property does not hold for theories of gravity, where observables near the boundary of the cauchy slice uniquely fix the state on the entire slice. the original formulation of the information paradox explicitly assumed the split property and we follow this assumption to isolate the precise error in hawking's argument. a similar assumption also underpins the monogamy paradox of mathur and amps. finally, the same assumption is used to support the common idea that the entanglement entropy of the region outside a black hole should follow a page curve. it is for this reason that computations of the page curve have been performed only in nonstandard theories of gravity, which include a nongravitational bath and massive gravitons. the fine-grained entropy at ${\mathcal{i}}^{+}$ does not obey a page curve for an evaporating black hole in standard theories of gravity but we discuss possibilities for coarse graining that might lead to a page curve in such cases. | failure of the split property in gravity and the information paradox |
we study the semi-classical thermodynamics of two-dimensional de sitter space (ds2) in jackiw-teitelboim (jt) gravity coupled to conformal matter. we extend the quasi-local formalism of brown and york to ds2, where a timelike boundary is introduced in the static patch to uniquely define conserved charges, including quasi-local energy. the boundary divides the static patch into two systems, a cosmological system and a black hole system, the former being unstable under thermal fluctuations while the latter is stable. a semi-classical quasi-local first law is derived, where the gibbons-hawking entropy is replaced by the generalized entropy. in the microcanonical ensemble the generalized entropy is stationary. further, we show the on-shell euclidean microcanonical action of a causal diamond in semi-classical jt gravity equals minus the generalized entropy of the diamond, hence extremization of the entropy follows from minimizing the action. thus, we provide a first principles derivation of the island rule for u(1) symmetric ds2 backgrounds, without invoking the replica trick. we discuss the implications of our findings for static patch de sitter holography. | quasi-local energy and microcanonical entropy in two-dimensional nearly de sitter gravity |
isolated objects in asymptotically flat spacetimes in general relativity are characterized by their conserved charges associated with the bondi-metzner-sachs (bms) group. these charges include total energy, linear momentum, intrinsic angular momentum and center-of-mass location, and, in addition, an infinite number of supermomentum charges associated with supertranslations. recently, it has been suggested that the bms symmetry algebra should be enlarged to include an infinite number of additional symmetries known as super-rotations. we show that the corresponding charges are finite and well defined, and can be divided into electric parity "super center-of-mass" charges and magnetic parity "superspin" charges. the supermomentum charges are associated with ordinary gravitational-wave memory, and the super center-of-mass charges are associated with total (ordinary plus null) gravitational-wave memory, in the terminology of bieri and garfinkle. superspin charges are associated with the ordinary piece of spin memory. some of these charges can give rise to black hole hair, as described by strominger and zhiboedov. we clarify how this hair evades the no-hair theorems. | conserved charges of the extended bondi-metzner-sachs algebra |
motivated by (i) more and more interest in strong gravitational lensing by supermassive black holes due to the achievement of eht observations, (ii) the ongoing popular topic on the possibility of lorentz symmetry being broken in gravitation and its consequences, we will apply the einstein bumblebee gravity with lorentz violation (lv) to the study of strong gravitational lensing effect and the black hole shadow of slowly rotating kerr-like black hole. in the strong gravitational lensing sector, we first calculate the deflection angle; then treating the slowly rotating kerr-like black hole as supermassive m87* black hole, we evaluate the gravitational lensing observables (position, separation and magnification) and the time delays between the relativistic images. in the black hole shadow sector, we show the effect of lv parameter on the luminosity of the black hole shadow and photon sphere using the infalling spherical accretion. moreover, we explore the dependence of various shadow observables on the lv parameter, and then give the possible constraint on the lv parameter by m87* black hole of eht observations. we find that the lv parameter shows significant effect on the strong gravitational lensing effect, the black hole shadow and photon sphere luminosity by accretion material. our results point out that the future generations of eht observation may help to distinguish the einstein bumblebee gravity from gr, and also give a possible constrain on the lv parameter. | strong gravitational lensing and shadow constraint from m87* of slowly rotating kerr-like black hole |
we show that the implications of the generalized uncertainty principle (gup) in the black hole physics are consistent with the predictions of the corpuscular theory of gravity, in which a black hole is conceived as a bose-einstein condensate of weakly interacting gravitons stuck at the critical point of a quantum phase transition. in particular, we compute such characteristic thermodynamic quantities as the temperature and the evaporation rate of a black hole. by comparing the results obtained in the two scenarios, we are able to estimate the gup deformation parameter β , which turns out to be of order unity, in agreement with the expectations of some models of string theory. we also comment on the sign of β , exploring the possibility of having a negative deformation parameter when a corpuscular quantum description of the gravitational interaction is assumed to be valid. | generalized uncertainty principle and corpuscular gravity |
we expand on our results in [1] to present a broad new class of gravitational observables in asymptotically anti-de sitter space living on general codimension-zero regions of the bulk spacetime. by taking distinct limits, these observables can reduce to well-studied holographic complexity proposals, e.g., the volume of the maximal slice and the action or spacetime volume of the wheeler-dewitt patch. as with the codimension-one family found in [1], these new observables display two key universal features for the thermofield double state: they grow linearly in time at late times and reproduce the switchback effect. hence we argue that any member of this new class of observables is an equally viable candidate as a gravitational dual of complexity. moreover, using the peierls construction, we show that variations of the codimension-zero and codimension-one observables are encoded in the gravitational symplectic form on the semi-classical phase-space, which can then be mapped to the cft. | complexity equals anything ii |
using the recently established formalism of a worldline quantum field theory description of the classical scattering of two spinless black holes, we compute the far-field time-domain waveform of the gravitational waves produced in the encounter at leading order in the post-minkowskian (weak field but generic velocity) expansion. we reproduce the previous results of kovacs and thorne in a highly economic way. then, using the waveform, we extract the leading-order total radiated angular momentum and energy (including differential results). our work may enable crucial improvements of gravitational-wave predictions in the regime of large relative velocities. | classical gravitational bremsstrahlung from a worldline quantum field theory |
variants of the black hole information paradox are studied in type iib string theory setups that realize four-dimensional gravity coupled to a bath. the setups are string theory versions of doubly-holographic karch/randall brane worlds, with black holes coupled to non-gravitating and gravitating baths. the 10d versions are based on fully backreacted solutions for configurations of d3, d5 and ns5 branes, and admit dual descriptions as n = 4 sym on a half space and 3d tρσ [su(n)] scfts. island contributions to the entanglement entropy of black hole radiation systems are identified through ryu/takayanagi surfaces and lead to page curves. analogs of the critical angles found in the karch/randall models are identified in 10d, as critical parameters in the brane configurations and dual field theories. | islands and page curves in 4d from type iib |
we investigate rotating effect on deconfinement phase transition in an einstein-maxwell-dilaton (emd) model in bottom-up holographic qcd approach. by constructing a rotating black hole, which is supposed to be dual to rotating strongly coupled nuclear matter, we investigate the thermodynamic quantities, including entropy density, pressure, energy density, trace anomaly, sound speed and specific heat for both pure gluon system and two-flavor system under rotation. it is shown that those thermodynamic quantities would be enhanced by large angular velocity. also, we extract the information of phase transition from those thermodynamic quantities, as well as the order parameter of deconfinement phase transition, i.e. the loop operators. it is shown that, in the t − ω plane, for two-flavor case with small chemical potential, the phase transition is always crossover. the transition temperature decreases slowly with angular velocity and chemical potential. for pure gluon system with zero chemical potential, the phase transition is always first order, while at finite chemical potential a critical end point (cep) will present in the t − ω plane. | gluodynamics and deconfinement phase transition under rotation from holography |
out-of-time-order correlation functions provide a proxy for diagnosing chaos in quantum systems. we propose and analyze an interferometric scheme for their measurement, using only local quantum control and no reverse time evolution. our approach utilizes a combination of ramsey interferometry and the recently demonstrated ability to directly measure renyi entropies. to implement our scheme, we present a pair of cold-atom-based experimental blueprints; moreover, we demonstrate that within these systems, one can naturally realize the transverse-field sherrington-kirkpatrick (tfsk) model, which exhibits certain similarities with fast scrambling black holes. we perform a detailed numerical study of scrambling in the tfsk model, observing an interesting interplay between the fast scrambling bound and the onset of spin-glass order. | interferometric approach to probing fast scrambling |
it was recently shown that a scalar field suitably coupled to the gauss-bonnet invariant g can undergo a spin-induced linear tachyonic instability near a kerr black hole. this instability appears only once the dimensionless spin j is sufficiently large, that is, j ≳0.5 . a tachyonic instability is the hallmark of spontaneous scalarization. focusing, for illustrative purposes, on a class of theories that do exhibit this instability, we show that stationary, rotating black hole solutions do indeed have scalar hair once the spin-induced instability threshold is exceeded, while black holes that lie below the threshold are described by the kerr solution. our results provide strong support for spin-induced black hole scalarization. | spin-induced scalarized black holes |
according to harlow and hayden [arxiv:1301.4504] the task of distilling information out of hawking radiation appears to be computationally hard despite the fact that the quantum state of the black hole and its radiation is relatively un-complex. we trace this computational difficulty to a geometric obstruction in the einstein-rosen bridge connecting the black hole and its radiation. inspired by tensor network models, we conjecture a precise formula relating the computational hardness of distilling information to geometric properties of the wormhole — specifically to the exponential of the difference in generalized entropies between the two non-minimal quantum extremal surfaces that constitute the obstruction. due to its shape, we call this obstruction the `python's lunch', in analogy to the reptile's postprandial bulge. | the python's lunch: geometric obstructions to decoding hawking radiation |
non-linear electrodynamics (nled) theories are well-motivated extensions of qed in the strong field regime, and have long been studied in the search for regular black hole (bh) solutions. we consider two well-studied and well-motivated nled models coupled to general relativity: the euler-heisenberg model and the bronnikov model. after carefully accounting for the effective geometry induced by the nled corrections, we determine the shadows of bhs within these two models. we then compare these to the shadow of the supermassive bh m87* recently imaged by the event horizon telescope collaboration. in doing so, we are able to extract upper limits on the black hole magnetic charge, thus providing novel constraints on fundamental physics from this new extraordinary probe. | magnetically charged black holes from non-linear electrodynamics and the event horizon telescope |
we study the propagation of probe scalar fields in the background of 4d einstein-gauss-bonnet black holes with anti-de sitter (ads) asymptotics and calculate the quasinormal modes. mainly, we show that the quasinormal spectrum consists of two different branches, a branch perturbative in the gauss-bonnet coupling constant α and another branch, nonperturbative in α . the perturbative branch consists of complex quasinormal frequencies that approximate the quasinormal frequencies of the schwarzschild ads black hole in the limit of a null coupling constant. on the other hand, the nonperturbative branch consists of purely imaginary frequencies and is characterized by the growth of the imaginary part when α decreases, diverging in the limit of null coupling constant; therefore they do not exist for the schwarzschild ads black hole. also, we find that the imaginary part of the quasinormal frequencies is always negative for both branches; therefore, the propagation of scalar fields is stable in this background. | perturbative and nonperturbative quasinormal modes of 4d einstein-gauss-bonnet black holes |
advances in our understanding of perturbation theory suggest the existence of a correspondence between classical general relativity and yang-mills theory. a concrete example of this correspondence, which is known as the double copy, was recently intro-duced for the case of stationary kerr-schild spacetimes. building on this foundation, we examine the simple time-dependent case of an accelerating, radiating point source. the gravitational solution, which generalises the schwarzschild solution, includes a non-trivial stress-energy tensor. this stress-energy tensor corresponds to a gauge theoretic current in the double copy. we interpret both of these sources as representing the radiative part of the field. furthermore, in the simple example of bremsstrahlung, we determine a scattering amplitude describing the radiation, maintaining the double copy throughout. our results provide the strongest evidence yet that the classical double copy is directly related to the bcj double copy for scattering amplitudes. | the double copy: bremsstrahlung and accelerating black holes |
we analysed the shadow cast by charged rotating black hole (bh) in presence of perfect fluid dark matter (pfdm). we studied the null geodesic equations and obtained the shadow of the charged rotating bh to see the effects of pfdm parameter γ, charge q and rotation parameter a, and it is noticed that the size as well as the shape of bh shadow is affected due to pfdm parameter, charge and rotation parameter. thus, it is seen that the presence of dark matter around a bh affects its spacetime. we also investigated the influence of all the parameters (pfdm parameter γ, bhs charge q and rotational parameter a) on effective potential, energy emission by graphical representation, and compare all the results with the non rotating case in usual general relativity. to this end, we have also explored the effect of pfdm on the deflection angle and the size of einstein rings. | shadow and deflection angle of charged rotating black hole surrounded by perfect fluid dark matter |
given at pitp 2018 summer program entitled "from qubits to spacetime." the first lecture describes the meaning of quantum complexity, the analogy between entropy and complexity, and the second law of complexity. lecture two reviews the connection between the second law of complexity and the interior of black holes. i discuss how firewalls are related to periods of non-increasing complexity which typically only occur after an exponentially long time. the final lecture is about the thermodynamics of complexity, and "uncomplexity" as a resource for doing computational work. i explain the remarkable power of "one clean qubit," in both computational terms and in space-time terms. the lectures can also be found online at \url{https://static.ias.edu/pitp/2018/node/1796.html} . | three lectures on complexity and black holes |
we give a pedagogical review of how concepts from quantum information theory build up the gravitational side of the anti-de sitter/conformal field theory correspondence. the review is self-contained in that it only presupposes knowledge of quantum mechanics and general relativity; other tools-including holographic duality itself-are introduced in the text. we have aimed to give researchers interested in entering this field a working knowledge sufficient for initiating original projects. the review begins with the laws of black hole thermodynamics, which form the basis of this subject, then introduces the ryu-takayanagi proposal, the jafferis-lewkowycz-maldacena-suh (jlms) relation, and subregion duality. we discuss tensor networks as a visualization tool and analyze various network architectures in detail. next, several modern concepts and techniques are discussed: rényi entropies and the replica trick, differential entropy and kinematic space, modular berry phases, modular minimal entropy, entanglement wedge cross-sections, bit threads, and others. we discuss the extent to which bulk geometries are fixed by boundary entanglement entropies, and analyze the relations such as the monogamy of mutual information, which boundary entanglement entropies must obey if a state has a semiclassical bulk dual. we close with a discussion of black holes, including holographic complexity, firewalls and the black hole information paradox, islands, and replica wormholes. | quantum information in holographic duality |
the concepts of operator size and computational complexity play important roles in the study of quantum chaos and holographic duality because they help characterize the structure of time-evolving heisenberg operators. it is particularly important to understand how these microscopically defined measures of complexity are related to notions of complexity defined in terms of a dual holographic geometry, such as complexity-volume (cv) duality. here we study partially entangled thermal states in the sachdev-ye-kitaev (syk) model and their dual description in terms of operators inserted in the interior of a black hole in jackiw-teitelboim (jt) gravity. we compare a microscopic definition of complexity in the syk model known as k-complexity to calculations using cv duality in jt gravity and find that both quantities show an exponential-to-linear growth behavior. we also calculate the growth of operator size under time evolution and find connections between size and complexity. while the notion of operator size saturates at the scrambling time, our study suggests that complexity, which is well defined in both quantum systems and gravity theories, can serve as a useful measure of operator evolution at both early and late times. | complexity growth of operators in the syk model and in jt gravity |
we discuss aspects of magnetically charged black holes in the standard model. for a range of charges, we argue that the electroweak symmetry is restored in the near horizon region. the extent of this phase can be macroscopic. if q is the integer magnetic charge, the fermions lead to order q massless two dimensional fermions moving along the magnetic field lines. these greatly enhance hawking radiation effects. | comments on magnetic black holes |
the links between the deformation parameter β of the generalized uncertainty principle (gup) to the two free parameters ω ^ and γ of the running newtonian coupling constant of the asymptotic safe gravity (asg) program, has been conducted recently in [phys. rev. d 105 (2022) 12, 124054. https://doi.org/10.1103/physrevd.105.124054] in this paper, we test these findings by calculating and examining the shadow and quasinormal modes of black holes, and demonstrate that the approach provides a theoretical framework for exploring the interplay between quantum gravity and gup. our results confirm the consistency of asg and gup, and offer new insights into the nature of black holes and their signatures. the implications of these findings for future studies in quantum gravity are also discussed. | investigating the connection between generalized uncertainty principle and asymptotically safe gravity in black hole signatures through shadow and quasinormal modes |
a novel four-dimensional einstein-gauss-bonnet gravity was formulated by glavan and lin (phys. rev. lett. 124:081301, 2020), which is intended to bypass the lovelock's theorem and to yield a non-trivial contribution to the four-dimensional gravitational dynamics. however, the validity and consistency of this theory has been called into question recently. we study a static and spherically symmetric black hole charged by a born-infeld electric field in the novel four-dimensional einstein-gauss-bonnet gravity. it is found that the black hole solution still suffers the singularity problem, since particles incident from infinity can reach the singularity. it is also demonstrated that the born-infeld charged black hole may be superior to the maxwell charged black hole to be a charged extension of the schwarzschild-ads-like black hole in this new gravitational theory. some basic thermodynamics of the black hole solution is also analyzed. besides, we regain the black hole solution in the regularized four-dimensional einstein-gauss-bonnet gravity proposed by lü and pang (arxiv:2003.11552). | born-infeld black holes in 4d einstein-gauss-bonnet gravity |
two-dimensional materials such as graphene and transition metal dichalcogenides have attracted great attention because of their rich physics and potential applications in next-generation nanoelectronic devices. the family of two-dimensional materials was recently joined by atomically thin black phosphorus which possesses high theoretical mobility and tunable bandgap structure. however, degradation of properties under atmospheric conditions and high-density charge traps in black phosphorus have largely limited its actual mobility thus hindering its future applications. here, we report the fabrication of stable sandwiched heterostructures by encapsulating atomically thin black phosphorus between hexagonal boron nitride layers to realize ultra-clean interfaces that allow a high field-effect mobility of ~1,350 cm2v-1 s-1 at room temperature and on-off ratios exceeding 105. at low temperatures, the mobility even reaches ~2,700 cm2v-1 s-1 and quantum oscillations in black phosphorus two-dimensional hole gas are observed at low magnetic fields. importantly, the sandwiched heterostructures ensure that the quality of black phosphorus remains high under ambient conditions. | high-quality sandwiched black phosphorus heterostructure and its quantum oscillations |
the (3 + 1)-dimensional einstein-gauss-bonnet theory of gravity which breaks the lorentz invariance in a theoretically consistent and observationally viable way has been recently suggested by aoki, gorji and mukohyama [5]. here we calculate grey-body factor for dirac, electromagnetic and gravitational fields and estimate the intensity of hawking radiation and lifetime for asymptotically flat black holes in this theory. positive coupling constant leads to much smaller evaporation rate and longer life-time of a black hole, while the negative one enhances hawking radiation. the grey-body factors for electromagnetic and dirac fields are smaller for larger values of the coupling constant. | grey-body factors and hawking radiation of black holes in 4d einstein-gauss-bonnet gravity |
a generic, noneccentric binary black hole (bbh) system emits gravitational waves (gws) that are completely described by seven intrinsic parameters: the black hole spin vectors and the ratio of their masses. simulating a bbh coalescence by solving einstein's equations numerically is computationally expensive, requiring days to months of computing resources for a single set of parameter values. since theoretical predictions of the gws are often needed for many different source parameters, a fast and accurate model is essential. we present the first surrogate model for gws from the coalescence of bbhs including all seven dimensions of the intrinsic noneccentric parameter space. the surrogate model, which we call nrsur7dq2, is built from the results of 744 numerical relativity simulations. nrsur7dq2 covers spin magnitudes up to 0.8 and mass ratios up to 2, includes all ℓ≤4 modes, begins about 20 orbits before merger, and can be evaluated in ∼50 ms . we find the largest nrsur7dq2 errors to be comparable to the largest errors in the numerical relativity simulations, and more than an order of magnitude smaller than the errors of other waveform models. our model, and more broadly the methods developed here, will enable studies that were not previously possible when using highly accurate waveforms, such as parameter inference and tests of general relativity with gw observations. | numerical relativity waveform surrogate model for generically precessing binary black hole mergers |
in this study, we observe that, in the presence of the string cloud parameter a and the quintessence parameter γ, with the equation of state parameter $ \omega_q={-2}/{3} $ , the radius of the shadow of the schwarzschild black hole increases as compared with that in the pure schwarzschild black hole case. the existence of both quintessential dark energy and the cloud of strings increases the shadow size; hence, the strength of the gravitational field around the schwarzschild black hole increases. using the data collected by the event horizon telescope (eht) collaboration for m87* and sgr a*, we obtain upper bounds on the values of a and γ. further, we see the effects of a and γ on the rate of emission energy for the schwarzschild black hole. we notice that the rate of emission energy is higher in the presence of clouds of strings and quintessence. moreover, we study the weak deflection angle using the gauss-bonnet theorem. we show the influence of a and γ on the weak deflection angle. we notice that both a and γ increase the deflection angle α. *g. mustafa acknowledges the grant no. zc304022919 to support his postdoctoral fellowship at zhejiang normal university. f.a. acknowledges the support of inha university in tashkent and research work has been supported by the visitor research fellowship at zhejiang normal university. this research is partly supported by research grant fz-20200929344; f-fa-2021-510 and f-fa-2021-432 of the uzbekistan ministry for innovative development | shadows and gravitational weak lensing by the schwarzschild black hole in the string cloud background with quintessential field |
due to the failure of thermodynamics for low temperature near-extremal black holes, it has long been conjectured that a "thermodynamic mass gap" exists between an extremal black hole and the lightest near-extremal state. for non-supersymmetric near-extremal black holes in einstein gravity, with an ads$_2$ throat, no such gap was found. rather, at that energy scale, the spectrum exhibits a continuum of states, up to non-perturbative corrections. in this paper, we compute the partition function of near-bps black holes in supergravity where the emergent, broken, symmetry is $psu(1,1|2)$. to reliably compute this partition function, we show that the gravitational path integral can be reduced to that of a $\mathcal n=4$ supersymmetric extension of the schwarzian theory, which we define and exactly quantize. in contrast to the non-supersymmetric case, we find that black holes in supergravity have a mass gap and a large extremal black hole degeneracy consistent with the bekenstein-hawking area. our results verify several string theory conjectures, concerning the scale of the mass gap and the counting of extremal micro-states. | the statistical mechanics of near-bps black holes |
in this paper we argue for a close connection between the non-existence of global symmetries in quantum gravity and a unitary resolution of the black hole information problem. in particular we show how the essential ingredients of recent calculations of the page curve of an evaporating black hole can be used to generalize a recent argument against global symmetries beyond the ads/cft correspondence to more realistic theories of quantum gravity. we also give several low-dimensional examples of quantum gravity theories which do not have a unitary resolution of the black hole information problem in the usual sense, and which therefore can and do have global symmetries. motivated by this discussion, we conjecture that in a certain sense euclidean quantum gravity is equivalent to holography. | global symmetry, euclidean gravity, and the black hole information problem |
the mass of a black hole has traditionally been identified with its energy. we describe a new perspective on black hole thermodynamics, one that identifies the mass of a black hole with chemical enthalpy, and the cosmological constant as thermodynamic pressure. this leads to an understanding of black holes from the viewpoint of chemistry, in terms of concepts such as van der waals fluids, reentrant phase transitions, and triple points. both charged and rotating black holes exhibit novel chemical-type phase behaviour, hitherto unseen. | black hole chemistry1 |
the existence of black holes and spacetime singularities is a fundamental issue in science. despite this, observations supporting their existence are scarce, and their interpretation is unclear. in this perspective we outline the case for black holes that has been made over the past few decades, and provide an overview of how well observations adjust to this paradigm. unsurprisingly, we conclude that observational proof for black holes is, by definition, impossible to obtain. however, just like popper's black swan, alternatives can be ruled out or confirmed to exist with a single observation. these observations are within reach. in the coming years and decades, we will enter an era of precision gravitational-wave physics with more sensitive detectors. just as accelerators have required larger and larger energies to probe smaller and smaller scales, more sensitive gravitational-wave detectors will probe regions closer and closer to the horizon, potentially reaching planck scales and beyond. what may be there, lurking? | tests for the existence of black holes through gravitational wave echoes |
asymptotically flat spacetimes admit both supertranslations and lorentz transformations as asymptotic symmetries. furthermore, they admit super-lorentz transformations, namely superrotations and superboosts, as outer symmetries associated with super-angular momentum and super-center-of-mass charges. in this paper, we present comprehensively the flux-balance laws for all such bms charges. we distinguish the poincaré flux-balance laws from the proper bms flux-balance laws associated with the three relevant memory effects defined from the shear, namely, the displacement, spin and center-of-mass memory effects. we scrutinize the prescriptions used to define the angular momentum and center-of-mass. in addition, we provide the exact form of all poincaré and proper bms flux-balance laws in terms of radiative symmetric tracefree multipoles. fluxes of energy, angular momentum and octupole super-angular momentum arise at 2.5pn, fluxes of quadrupole supermomentum arise at 3pn and fluxes of momentum, center-of-mass and octupole super-center-of-mass arise at 3.5pn. we also show that the bms flux-balance laws lead to integro-differential consistency constraints on the radiation-reaction forces acting on the sources. finally, we derive the exact form of all bms charges for both an initial kerr binary and a final kerr black hole in an arbitrary lorentz and supertranslation frame, which allows to derive exact constraints on gravitational waveforms produced by binary black hole mergers from each bms flux-balance law. | the poincaré and bms flux-balance laws with application to binary systems |
we explore the spacetime structure near nonextremal horizons in any spacetime dimension greater than two and discover a wealth of novel results: (i) different boundary conditions are specified by a functional of the dynamical variables, describing inequivalent interactions at the horizon with a thermal bath. (ii) the near horizon algebra of a set of boundary conditions, labeled by a parameter s , is given by the semidirect sum of diffeomorphisms at the horizon with "spin-s supertranslations." for s =1 we obtain the first explicit near horizon realization of the bondi-metzner-sachs algebra. (iii) for another choice, we find a nonlinear extension of the heisenberg algebra, generalizing recent results in three spacetime dimensions. this algebra allows us to recover the aforementioned (linear) ones as composites. (iv) these examples allow us to equip not only black holes, but also cosmological horizons with soft hair. we also discuss implications of soft hair for black hole thermodynamics and entropy. | spacetime structure near generic horizons and soft hair |
we review recent progress on the information paradox. we explain why exponentially small correlations in the radiation emitted by a black hole are sufficient to resolve the original paradox put forward by hawking. we then describe a refinement of the paradox that makes essential reference to the black-hole interior. this analysis leads to a broadly-applicable physical principle: in a theory of quantum gravity, a copy of all the information on a cauchy slice is also available near the boundary of the slice. this principle can be made precise and established -- under weak assumptions, and using only low-energy techniques -- in asymptotically global ads and in four dimensional asymptotically flat spacetime. when applied to black holes, this principle tells us that the exterior of the black hole always retains a complete copy of the information in the interior. we show that accounting for this redundancy provides a resolution of the information paradox for evaporating black holes and, conversely, that ignoring this redundancy leads to paradoxes even in the absence of black holes. we relate this perspective to recent computations of the page curve for holographic cfts coupled to nongravitational baths. but we argue that such models may provide an inaccurate picture of the rate at which information can be extracted from evaporating black holes in asymptotically flat space. we discuss large black holes dual to typical states in ads/cft and the new paradoxes that arise in this setting. these paradoxes also extend to the eternal black hole. they can be resolved by assuming that the map between the boundary cft and the black-hole interior is state dependent. we discuss the consistency of state-dependent bulk reconstructions. we conclude by examining the viability of arguments for firewalls, fuzzballs and other kinds of structure at the horizon. | lessons from the information paradox |
higher spin gravity refers to extensions of gravity including at least one field of spin greater than two. these extensions are expected to provide manageable models of quantum gravity thanks to the infinite-dimensional (higher spin) gauge symmetry constraining them. one of the key aspects of higher spin gravity/symmetry is the range and diversity of topics it embraces: (a) higher spin fields play a role in quantum gravity, ads/cft, string theory and are expected to have important consequences in cosmology and black hole physics; (b) higher spin symmetry finds applications in conformal field theories, condensed matter systems and dualities therein; (c) these models often rely on tools developed in the study of the mathematical foundations of qft or in pure mathematics: from deformation quantization and non-commutative geometry to conformal geometry, graded geometry (including bv-brst quantization), and geometry of pdes. recent exciting applications also involve (d) modelling the coalescence of black hole binaries as scattering of massive higher spin particles. | snowmass white paper: higher spin gravity and higher spin symmetry |
in this study, the gravitational deflection angle of photons in the weak field limit (or the weak deflection angle) and shadow cast by the electrically charged and spherically symmetric static kiselev black hole (bh) in the string cloud background are investigated. the influences of the bh charge q, quintessence parameter γ, and string cloud parameter a on the weak deflection angle are studied using the gauss-bonnet theorem, in addition to studying the influences on the radius of photon spheres and size of the bh shadow in the spacetime geometry of the charged-kiselev bh in string clouds. moreover, we study the effects of plasma (uniform and non-uniform) on the weak deflection angle and shadow cast by the charged-kiselev bh surrounded by the clouds of strings. in the presence of a uniform/nonuniform plasma medium, an increase in the string cloud parameter a increases the deflection angle α. in contrast, a decrease in the bh charge q decreases the deflection angle. further, we observe that an increase in the bh charge q causes a decrease in the size of the shadow of the bh. we notice that, with an increase in the values of the parameters γ and a, the size of the bh shadow increases, and therefore, the intensity of the gravitational field around the charged-kiselev bh in string clouds increases. thus, the gravitational field of the charged-kiselev bh in the string cloud background is stronger than the field produced by the pure reissner-nordstrom bh. moreover, we use the data released by the event horizon telescope (eht) collaboration, for the supermassive bhs m87* and sgr a*, to obtain constraints on the values of the parameters γ and a. *partly supported by the uzbekistan ministry for innovative development (fz-20200929344 and f-fa-2021-510). i.h. is grateful to the institute of mathematics, university of aberdeen, scotland, uk, where a part of this study was done under the imu-cdc individual travel support program. g.m. is supported by postdoctoral fellowship of zhejiang normal university (zc304022919). a.{ö}. would like to acknowledge the contribution of the cost action ca18108 - quantum gravity phenomenology in the multi-messenger approach (qg-mm) | weak deflection angle and shadow cast by the charged-kiselev black hole with cloud of strings in plasma |
when an incident wave scatters off of an obstacle, it is partially reflected and partially transmitted. in theory, if the obstacle is rotating, waves can be amplified in the process, extracting energy from the scatterer. here we describe in detail the first laboratory detection of this phenomenon, known as superradiance. we observed that waves propagating on the surface of water can be amplified after being scattered by a draining vortex. the maximum amplification measured was 14% +/- 8%, obtained for 3.70 hz waves, in a 6.25-cm-deep fluid, consistent with the superradiant scattering caused by rapid rotation. we expect our experimental findings to be relevant to black-hole physics, since shallow water waves scattering on a draining fluid constitute an analogue of a black hole, as well as to hydrodynamics, due to the close relation to over-reflection instabilities. | rotational superradiant scattering in a vortex flow |
we analyze the algebra of boundary observables in canonically quantised jt gravity with or without matter. in the absence of matter, this algebra is commutative, generated by the adm hamiltonian. after coupling to a bulk quantum field theory, it becomes a highly noncommutative algebra of type ii$_\infty$ with a trivial center. as a result, density matrices and entropies on the boundary algebra are uniquely defined up to, respectively, a rescaling or shift. we show that this algebraic definition of entropy agrees with the usual replica trick definition computed using euclidean path integrals. unlike in previous arguments that focused on $\mathcal{o}(1)$ fluctuations to a black hole of specified mass, this type ii$_\infty$ algebra describes states at all temperatures or energies. we also consider the role of spacetime wormholes. one can try to define operators associated with wormholes that commute with the boundary algebra, but this fails in an instructive way. in a regulated version of the theory, wormholes and topology change can be incorporated perturbatively. the bulk hilbert space $\mathcal{h}_\mathrm{bulk}$ that includes baby universe states is then much bigger than the space of states $\mathcal{h}_\mathrm{bdry}$ accessible to a boundary observer. however, to a boundary observer, every pure or mixed state on $\mathcal{h}_\mathrm{bulk}$ is equivalent to some pure state in $\mathcal{h}_\mathrm{bdry}$. | algebras and states in jt gravity |
we construct the boundary phase space in d-dimensional einstein gravity with a generic given co-dimension one null surface n as the boundary. the associated boundary symmetry algebra is a semi-direct sum of diffeomorphisms of n and weyl rescalings. it is generated by d towers of surface charges that are generic functions over n . these surface charges can be rendered integrable for appropriate slicings of the phase space, provided there is no graviton flux through n . in one particular slicing of this type, the charge algebra is the direct sum of the heisenberg algebra and diffeomorphisms of the transverse space, n v for any fixed value of the advanced time v. finally, we introduce null surface expansion- and spin-memories, and discuss associated memory effects that encode the passage of gravitational waves through n , imprinted in a change of the surface charges. | null boundary phase space: slicings, news & memory |
we derive an approximate analytical formula for the spectral density of the q -body sachdev-ye-kitaev (syk) model obtained by summing a class of diagrams representing leading intersecting contractions. this expression agrees with that of q -hermite polynomials, with q a nontrivial function of q ≥2 and the number of majorana fermions n . numerical results, obtained by exact diagonalization, are in excellent agreement with this approximate analytical spectral density even for relatively small n ∼8 . for n ≫1 and not close to the edge of the spectrum, we find that the approximate analytical spectral density simplifies to ρasym(e )=exp [2 arcsin2(e /e0)/log η ] , where η (n ,q ) is the suppression factor of the contribution of intersecting wick contractions relative to nested contractions and e0 is the ground-state energy per particle. this spectral density reproduces the known result for the free energy in the large-q and large-n limit at arbitrary values of the temperature. in the infrared region, where the syk model is believed to have a gravity dual, the analytical spectral density is given by ρ (e )∼sinh [2 π √{2 }√{(1 -e /e0)/(-log η ) }] . it therefore has a square-root edge, as in random matrix ensembles, followed by an exponential growth, a distinctive feature of black holes and also of low-energy nuclear excitations. results for level statistics in this region confirm the agreement with random matrix theory. physically this is a signature that, for sufficiently long times, the syk model and its gravity dual evolve to a fully ergodic state whose dynamics only depends on the global symmetry of the system. our results strongly suggest that random matrix correlations are a universal feature of quantum black holes and that the syk model, combined with holography, may be relevant to modeling certain aspects of the nuclear dynamics. | analytical spectral density of the sachdev-ye-kitaev model at finite n |
the classification of critical points of charged topological black holes (tbhs) in anti-de sitter spacetime (ads) under the power maxwell invariant (pmi)-massive gravity is accomplished within the framework of black hole chemistry (bhc). considering the grand canonical ensemble (gce), we show that d =4 black hole have only one topological class, whereas d ≥5 black holes belong to two different topology classes. furthermore, the conventional critical point characterized by negative topological charge coincides with the maximum extreme point of temperature; and the novel critical point featuring opposite topological charge corresponds to the minimum extreme point of temperature. with increasing pressure, new phases emerge at the novel critical point while disappear from the conventional one. moreover, a atypical van der waals (vdw) behavior is found in d ≥6 dimensions, and the anomaly disappears at the traditional critical point. in the limit of nonlinearity parameter s →1 , different topology classes are only obtained in the gce and they may not exist within the canonical ensemble. with the absence of electric potential φ , the neutral tbhs share the same topological classification results as the charged tbhs in the gce of maxwell-massive gravity. | topology of nonlinearly charged black hole chemistry via massive gravity |
we consider the capacity of entanglement in models related with the gravitational phase transitions. the capacity is labeled by the replica parameter which plays a similar role to the inverse temperature in thermodynamics. in the end of the world brane model of a radiating black hole the capacity has a peak around the page time indicating the phase transition between replica wormhole geometries of different types of topology. similarly, in a moving mirror model describing hawking radiation the capacity typically shows a discontinuity when the dominant saddle switches between two phases, which can be seen as a formation of island regions. in either case we find the capacity can be an invaluable diagnostic for a black hole evaporation process. | probing hawking radiation through capacity of entanglement |
we present a wormhole solution in four dimensions. it is a solution of an einstein maxwell theory plus charged massless fermions. the fermions give rise to a negative casimir-like energy, which makes the wormhole possible. it is a long wormhole that does not lead to causality violations in the ambient space. it can be viewed as a pair of entangled near extremal black holes with an interaction term generated by the exchange of fermion fields. the solution can be embedded in the standard model by making its overall size small compared to the electroweak scale. | traversable wormholes in four dimensions |
recently it was proposed that the entanglement entropy of the hawking radiation contains the information of a region including the interior of the event horizon, which is called "island." in studies of the entanglement entropy of the hawking radiation, the total system in the black hole geometry is separated into the hawking radiation and black hole. in this paper, we study the entanglement entropy of the black hole in the asymptotically flat schwarzschild spacetime. consistency with the island rule for the hawking radiation implies that the information of the black hole is located in a different region than the island. we found an instability of the island in the calculation of the entanglement entropy of the region outside a surface near the horizon. this implies that the region contains all the information of the total system and the information of the black hole is localized on the surface. thus the surface would be interpreted as the stretched horizon. this structure also resembles black holes in the ads spacetime with an auxiliary flat spacetime, where the information of the black hole is localized at the interface between the ads spacetime and the flat spacetime. | islands and stretched horizon |
we perform a feynman diagram calculation of the two-loop scattering amplitude for gravitationally interacting massive particles in the classical limit. conveniently, we are able to sidestep the most taxing diagrams by exploiting the test-particle limit in which the system is fully characterized by a particle propagating in a schwarzschild spacetime. we assume a general choice of graviton field basis and gauge fixing that contains as a subset the well-known dedonder gauge and its various cousins. as a highly nontrivial consistency check, all gauge parameters evaporate from the final answer. moreover, our result exactly matches that of bern et al. [39], here verified up to sixth post-newtonian order while also reproducing the same unique velocity resummation at third post-minkowksian order. | classical gravitational scattering at o (g3) from feynman diagrams |
we study the population properties of merging binary black holes in the second ligo-virgo gravitational-wave transient catalog assuming they were all formed dynamically in gravitationally bound clusters. using a phenomenological population model, we infer the mass and spin distribution of first-generation black holes, while self-consistently accounting for hierarchical mergers. considering a range of cluster masses, we see compelling evidence for hierarchical mergers in clusters with escape velocities ≳100 km s-1. for our most probable cluster mass, we find that the catalog contains at least one second-generation merger with 99% credibility. we find that the hierarchical model is preferred over an alternative model with no hierarchical mergers (bayes factor ${ \mathcal b }\gt 1400$ ) and that gw190521 is favored to contain two second-generation black holes with odds ${ \mathcal o }\gt 700$ , and gw190519, gw190602, gw190620, and gw190706 are mixed-generation binaries with ${ \mathcal o }\gt 10$ . however, our results depend strongly on the cluster escape velocity, with more modest evidence for hierarchical mergers when the escape velocity is ≲100 km s-1. assuming that all binary black holes are formed dynamically in globular clusters with escape velocities on the order of tens of km s-1, gw190519 and gw190521 are favored to include a second-generation black hole with odds ${ \mathcal o }\gt 1$ . in this case, we find that 99% of black holes from the inferred total population have masses that are less than 49m⊙, and that this constraint is robust to our choice of prior on the maximum black hole mass. | evidence for hierarchical black hole mergers in the second ligo-virgo gravitational wave catalog |
we study a precise and computationally tractable notion of operator complexity in holographic quantum theories, including the ensemble dual of jackiw-teitelboim gravity and two-dimensional holographic conformal field theories. this is a refined, "microcanonical" version of k-complexity that applies to theories with infinite or continuous spectra (including quantum field theories), and in the holographic theories we study exhibits exponential growth for a scrambling time, followed by linear growth until saturation at a time exponential in the entropy — a behavior that is characteristic of chaos. we show that the linear growth regime implies a universal random matrix description of the operator dynamics after scrambling. our main tool for establishing this connection is a "complexity renormalization group" framework we develop that allows us to study the effective operator dynamics for different timescales by "integrating out" large k-complexities. in the dual gravity setting, we comment on the empirical match between our version of k-complexity and the maximal volume proposal, and speculate on a connection between the universal random matrix theory dynamics of operator growth after scrambling and the spatial translation symmetry of smooth black hole interiors. | random matrix theory for complexity growth and black hole interiors |
recently the ligo and virgo collaborations reported the observation of gravitational-wave signal corresponding to the inspiral and merger of two black holes, resulting into formation of the final black hole. it was shown that the observations are consistent with the einstein theory of gravity with high accuracy, limited mainly by the statistical error. angular momentum and mass of the final black hole were determined with rather large allowance of tens of percents. here we shall show that this indeterminacy in the range of the black-hole parameters allows for some non-negligible deformations of the kerr spacetime leading to the same frequencies of the black-hole ringing. this means that at the current precision of the experiment there remains some possibility for alternative theories of gravity. | detection of gravitational waves from black holes: is there a window for alternative theories? |
these are lecture notes from a weeklong course in quantum complexity theory taught at the bellairs research institute in barbados, february 21-25, 2016. the focus is quantum circuit complexity---i.e., the minimum number of gates needed to prepare a given quantum state or apply a given unitary transformation---as a unifying theme tying together several topics of recent interest in the field. those topics include the power of quantum proofs and advice states; how to construct quantum money schemes secure against counterfeiting; and the role of complexity in the black-hole information paradox and the ads/cft correspondence (through connections made by harlow-hayden, susskind, and others). the course was taught to a mixed audience of theoretical computer scientists and quantum gravity / string theorists, and starts out with a crash course on quantum information and computation in general. | the complexity of quantum states and transformations: from quantum money to black holes |
we find a mechanism by which antibranes placed in a warped deformed conifold throat can destroy the stabilization of the size of the sphere at the tip, collapsing it to zero size. this conifold destabilization mechanism can be avoided by turning on a large amount of flux on the sphere, but tadpole cancelation makes this incompatible with a hierarchy of scales in a type iib flux compactification. this indicates that antibrane uplift cannot be used to construct stable de sitter vacua with a small cosmological constant in perturbative string theory. the values of v and v' for these kklt-like scenarios can be parametrically small, but we find that v'/v is still consistent with the de sitter swampland conjecture. our results also suggest that there should exist a klebanov-strassler black hole, holographically dual to a deconfined phase with spontaneously broken chiral symmetry. | uplifting runaways |
we use conformal supergravity techniques to study four-derivative corrections in four-dimensional gauged supergravity. we show that the four-derivative lagrangian for the propagating degrees of freedom of the n = 2 gravity multiplet is determined by two real dimensionless constants. we demonstrate that all solutions of the two-derivative equations of motion in the supergravity theory also solve the four-derivative equations of motion. these results are then applied to explicitly calculate the regularized on-shell action for any asymptotically locally ads4 solution of the two-derivative equations of motion. the four-derivative terms in the supergravity lagrangian modify the entropy and other thermodynamic observables for the black hole solutions of the theory. we calculate these corrections explicitly and demonstrate that the quantum statistical relation holds for general stationary black holes in the presence of the four-derivative corrections. employing an embedding of this supergravity model in m-theory we show how to use supersymmetric localization results in the holographically dual three-dimensional scft to determine the unknown coefficients in the four-derivative supergravity action. this in turn leads to new detailed results for the first subleading n1/2 correction to the large n partition function of a class of three-dimensional scfts on compact euclidean manifolds. in addition, we calculate explicitly the first subleading correction to the bekenstein-hawking entropy of asymptotically ads4 black holes in m-theory. we also discuss how to add matter multiplets to the supergravity theory in the presence of four-derivative terms and to generalize some of these results to six- and higher-derivative supergravity. | higher-derivative supergravity, ads4 holography, and black holes |
we study the euclidean gravitational path integral computing the rényi entropy and analyze its behavior under small variations. we argue that, in einstein gravity, the extremality condition can be understood from the variational principle at the level of the action, without having to solve explicitly the equations of motion. this set-up is then generalized to arbitrary theories of gravity, where we show that the respective entanglement entropy functional needs to be extremized. we also extend this result to all orders in newton's constant gn, providing a derivation of quantum extremality. understanding quantum extremality for mixtures of states provides a generalization of the dual of the boundary modular hamiltonian which is given by the bulk modular hamiltonian plus the area operator, evaluated on the so-called modular extremal surface. this gives a bulk prescription for computing the relative entropies to all orders in gn. we also comment on how these ideas can be used to derive an integrated version of the equations of motion, linearized around arbitrary states. | entropy, extremality, euclidean variations, and the equations of motion |
we develop a novel amplitude bootstrap technique manifestly free of unphysical poles for classically spinning particles interacting with gravitons utilizing only the gauge/gravity double-copy and physical factorization limits. combined with non-factorization polynomial contact contributions from physical data for kerr black holes, we can address high-spin-order covariant gravitational compton amplitudes, identifying a pattern for the amplitude that we believe could extend to all orders in spin. finally, we outline applications and outstanding questions. | covariant compton amplitudes in gravity with classical spin |
we prove the non-linear asymptotic stability of the schwarzschild family as solutions to the einstein vacuum equations in the exterior of the black hole region: general vacuum initial data, with no symmetry assumed, sufficiently close to schwarzschild data evolve to a vacuum spacetime which (i) possesses a complete future null infinity $\mathcal{i}^+$ (whose past $j^-(\mathcal{i}^+)$ is moreover bounded by a regular future complete event horizon $\mathcal{h}^+$), (ii) remains close to schwarzschild in its exterior, and (iii) asymptotes back to a member of the schwarzschild family as an appropriate notion of time goes to infinity, provided that the data are themselves constrained to lie on a teleologically constructed codimension-$3$ "submanifold" of moduli space. this is the full nonlinear asymptotic stability of schwarzschild since solutions not arising from data lying on this submanifold should by dimensional considerations approach a kerr spacetime with rotation parameter $a\neq 0$, i.e. such solutions cannot satisfy (iii). the proof employs teleologically normalised double null gauges, is expressed entirely in physical space and makes essential use of the analysis in our previous study of the linear stability of the kerr family around schwarzschild [dhr], as well as techniques developed over the years to control the non-linearities of the einstein equations. the present work, however, is entirely self-contained. in view of the recent [dhr19, tdcsr20] our approach can be applied to the full non-linear asymptotic stability of the subextremal kerr family. | the non-linear stability of the schwarzschild family of black holes |
the wkb approach for finding quasinormal modes of black holes, suggested in schutz and will (1985 astrophys. j. lett. 291 l33-6) by schutz and will at the first order and later developed to higher orders (iyer and will 1987 phys. rev. d 35 3621; konoplya 2003 phys. rev. d 68 024018; matyjasek and opala 2017 phys. rev. d 96 024011), became popular during the past decades, because, unlike more sophisticated numerical approaches, it is automatic for different effective potentials and mostly provides sufficient accuracy. at the same time, the seeming simplicity of the wkb approach resulted in appearance of a big number of partially misleading papers, where the wkb formula was used beyond its scope of applicability. here we review various situations in which the wkb formula can or cannot bring us to reliable conclusions. as the wkb series converges only asymptotically, there is no mathematically strict criterium for evaluation of an error. therefore, here we are trying to introduce a number of practical recipes instead and summarize cases in which higher wkb orders improve accuracy. we show that averaging of the padé approximations, suggested first by matyjasek and opala (2017 phys. rev. d 96 024011), leads to much higher accuracy of the wkb approach, estimate the error and present the automatic code (the mathematica®package with the wkb formula of 13th order and padé approximations ready for calculation of the quasinormal modes and grey-body factors, as well as examples of such calculations for the schwarzschild black hole are publicly available to download from https://goo.gl/nykygl) which computes quasinormal modes and grey-body factors. | higher order wkb formula for quasinormal modes and grey-body factors: recipes for quick and accurate calculations |
the evaporation of black holes raises a number of conceptual issues, most of them related to the final stages of evaporation, where the interplay between the central singularity and hawking radiation cannot be ignored. regular models of black holes replace the central singularity with a nonsingular spacetime region, in which an effective classical geometric description is available. it has been argued that these models provide an effective, but complete, description of the evaporation of black holes at all times up to their eventual disappearance. however, here we point out that known models fail to be self-consistent: the regular core is exponentially unstable against perturbations with a finite timescale, while the evaporation time is infinite, therefore making the instability impossible to prevent. we also discuss how to overcome these difficulties, highlighting that this can be done only at the price of accepting that these models cannot be fully predictive regarding the final stages of evaporation. | on the viability of regular black holes |
we argue that the gravitational shock wave computation used to extract the scrambling rate in strongly coupled quantum theories with a holographic dual is directly related to probing the system's hydrodynamic sound modes. the information recovered from the shock wave can be reconstructed in terms of purely diffusionlike, linearized gravitational waves at the horizon of a single-sided black hole with specific regularity-enforced imaginary values of frequency and momentum. in two-derivative bulk theories, this horizon "diffusion" can be related to late-time momentum diffusion via a simple relation, which ceases to hold in higher-derivative theories. we then show that the same values of imaginary frequency and momentum follow from a dispersion relation of a hydrodynamic sound mode. the frequency, momentum, and group velocity give the holographic lyapunov exponent and the butterfly velocity. moreover, at this special point along the sound dispersion relation curve, the residue of the retarded longitudinal stress-energy tensor two-point function vanishes. this establishes a direct link between a hydrodynamic sound mode at an analytically continued, imaginary momentum and the holographic butterfly effect. furthermore, our results imply that infinitely strongly coupled, large-nc holographic theories exhibit properties similar to classical dilute gases; there, late-time equilibration and early-time scrambling are also controlled by the same dynamics. | black hole scrambling from hydrodynamics |
we compute the scattering amplitude for classical black-hole scattering to third order in the post-minkowskian expansion, keeping all terms needed to derive the scattering angle to that order from the eikonal formalism. our results confirm a conjectured relation between the real and imaginary parts of the amplitude by di vecchia, heissenberg, russo, and veneziano, and are in agreement with a recent computation by damour based on radiation reaction in general relativity. | the amplitude for classical gravitational scattering at third post-minkowskian order |
we construct asymptotically flat, spinning, regular on and outside an event horizon, scalarized black holes (sbhs) in extended scalar-tensor-gauss-bonnet models. they reduce to kerr bhs when the scalar field vanishes. for an illustrative choice of nonminimal coupling, we scan the domain of existence. for each value of spin, sbhs exist in an interval between two critical masses, with the lowest one vanishing in the static limit. non-uniqueness with kerr bhs of equal global charges is observed; the sbhs are entropically favoured. this suggests that sbhs form dynamically from the spontaneous scalarization of kerr bhs, which are prone to a scalar-triggered tachyonic instability, below the largest critical mass. phenomenologically, the introduction of bh spin damps the maximal observable difference between comparable scalarized and vacuum bhs. in the static limit, (perturbatively stable) sbhs can store over 20% of the spacetime energy outside the event horizon; in comparison with schwarzschild bhs, their geodesic frequency at the isco can differ by a factor of 2.5 and deviations in the shadow areal radius may top 40%. as the bh spin grows, low mass sbhs are excluded, and the maximal relative differences decrease, becoming of the order of a few percent for dimensionless spin j ≳0.5 . this reveals a spin selection effect: non-gr effects are only significant for low spin. we discuss if and how the recently measured shadow size of the m87 supermassive bh constrains the length scale of the gauss-bonnet coupling. | spontaneously scalarized kerr black holes in extended scalar-tensor-gauss-bonnet gravity |
large, energy-dependent x-ray polarisation is observed in 4u 1630-47, a black hole in an x-ray binary, in the high-soft emission state. in this state, x-ray emission is believed to be dominated by a thermal, geometrically thin, optically thick accretion disc. however, the observations with the imaging x-ray polarimetry explorer (ixpe) reveal an unexpectedly high polarisation degree, rising from 6% at 2 kev to 10% at 8 kev, which cannot be reconciled with standard models of thin accretion discs. we argue that an accretion disc with an only partially ionised atmosphere flowing away from the disc at mildly relativistic velocities can explain the observations. | the high polarisation of the x-rays from the black hole x-ray binary 4u 1630-47 challenges standard thin accretion disc scenario |
in order to study the pseudo entropy of timelike subregions holographically, the previous smooth space-like extremal surface was recently generalized to mix space-like and time-like segments and the area becomes complex value. this paper finds that, if one tries to use such kind of piecewise smooth extremal surfaces to compute timelike entanglement entropy holographically, the complex area is not unique in general. we then generalize the original holographic proposal of spacelike entanglement entropy to pick up a unique area from all allowed "space-like+time-like" piecewise smooth extremal surfaces for a timelike subregion. we give some concrete examples to show the correctness of our proposal. | on holographic time-like entanglement entropy |
in classical general relativity (gr), an observer falling into an astrophysical black hole is not expected to experience anything dramatic as she crosses the event horizon. however, tentative resolutions to problems in quantum gravity, such as the cosmological constant problem, or the black hole information paradox, invoke significant departures from classicality in the vicinity of the horizon. it was recently pointed out that such near-horizon structures can lead to late-time echoes in the black hole merger gravitational wave signals that are otherwise indistinguishable from gr. we search for observational signatures of these echoes in the gravitational wave data released by the advanced laser interferometer gravitational-wave observatory (ligo), following the three black hole merger events gw150914, gw151226, and lvt151012. in particular, we look for repeating damped echoes with time delays of 8 m log m (+spin corrections, in planck units), corresponding to planck-scale departures from gr near their respective horizons. accounting for the "look elsewhere" effect due to uncertainty in the echo template, we find tentative evidence for planck-scale structure near black hole horizons at false detection probability of 1% (corresponding to 2.5 σ | echoes from the abyss: tentative evidence for planck-scale structure at black hole horizons |
we present two particular decoding procedures for reconstructing a quantum state from the hawking radiation in the hayden-preskill thought experiment. we work in an idealized setting and represent the black hole and its entangled partner by $n$ epr pairs. the first procedure teleports the state thrown into the black hole to an outside observer by post-selecting on the condition that a sufficient number of epr pairs remain undisturbed. the probability of this favorable event scales as $1/d_{a}^2$, where $d_a$ is the hilbert space dimension for the input state. the second procedure is deterministic and combines the previous idea with grover's search. the decoding complexity is $\mathcal{o}(d_{a}\mathcal{c})$ where $\mathcal{c}$ is the size of the quantum circuit implementing the unitary evolution operator $u$ of the black hole. as with the original (non-constructive) decoding scheme, our algorithms utilize scrambling, where the decay of out-of-time-order correlators (otocs) guarantees faithful state recovery. | efficient decoding for the hayden-preskill protocol |
the discovery of new four-dimensional black hole solutions presents a new approach to understand the gauss-bonnet gravity in low dimensions. in this paper, we test the gauss-bonnet gravity by studying the phase transition and microstructures for the four-dimensional charged anti-de sitter black hole. in the extended phase space, where the cosmological constant and the gauss-bonnet coupling parameter are treated as thermodynamic variables, we find that the thermodynamic first law and the corresponding smarr formula are satisfied. both in the canonical ensemble and grand canonical ensemble, we observe the small-large black hole phase transition, which is similar to the case of the van der walls fluid. this phase transition can also appear in the neutral black hole system. furthermore, we construct the ruppeiner geometry, and find that besides the attractive interaction, the repulsive interaction can also dominate among the microstructures for the small black hole with high temperature in a charged or neutral black hole system. this is quite different from the five-dimensional neutral black hole, for which only dominant attractive interaction can be found. the critical behaviors of the normalized scalar curvature are also examined. these results will shed new light into the characteristic property of four-dimensional gauss-bonnet gravity. | extended thermodynamics and microstructures of four-dimensional charged gauss-bonnet black hole in ads space |
we obtain exact bardeen black holes to the regularized $4d$ einstein--gauss--bonnet (egb) gravity minimally coupled with the nonlinear electrodynamics (ned). in turn, we analyze the horizon structure to determine the effect of gb parameter $\alpha$ on the minimum cutoff values of mass, $m_0$, and magnetic monopole charge, $g_0$, for the existence of a black hole horizon. we obtain an exact expression for thermodynamic quantities, namely, hawking temperature $t_+$, entropy $s_+$, helmholtz free energy $f_+$, and specific heat $c_+$ associated with the black hole horizon, and they show significant deviations from the $4d$ egb case owing to ned. interestingly, there exists a critical value of horizon radius, $r_+^{c}$, corresponding to the local maximum of hawking temperature, at which heat capacity diverges, confirming the second-order phase transition. a discussion on the black holes of alternate regularized $4d$ egb gravity belonging to the scalar-tensor theory is appended. | bardeen black holes in the regularized $4d$ einstein--gauss--bonnet gravity |
this letter describes a model-agnostic search for pairs of jets (dijets) produced by resonant and non-resonant phenomena beyond the standard model in 3.6 fb-1 of proton-proton collisions with a centre-of-mass energy of √{ s} = 13 tev recorded by the atlas detector at the large hadron collider. the distribution of the invariant mass of the two leading jets is examined for local excesses above a data-derived estimate of the smoothly falling prediction of the standard model. the data are also compared to a monte carlo simulation of standard model angular distributions derived from the rapidity of the two jets. no evidence of anomalous phenomena is observed in the data, which are used to exclude, at 95% cl, quantum black holes with threshold masses below 8.3 tev, 8.1 tev, or 5.1 tev in three different benchmark scenarios; resonance masses below 5.2 tev for excited quarks, 2.6 tev in a w‧ model, a range of masses starting from mz‧ = 1.5 tev and couplings from gq = 0.2 in a z‧ model; and contact interactions with a compositeness scale below 12.0 tev and 17.5 tev respectively for destructive and constructive interference between the new interaction and qcd processes. these results significantly extend the atlas limits obtained from 8 tev data. gaussian-shaped contributions to the mass distribution are also excluded if the effective cross-section exceeds values ranging from approximately 50-300 fb for masses below 2 tev to 2-20 fb for masses above 4 tev. | search for new phenomena in dijet mass and angular distributions from pp collisions at √{ s} = 13 tev with the atlas detector |
we suggest that the holographic principle, combined with recent technological advances in atomic, molecular, and optical physics, can lead to experimental studies of quantum gravity. as a specific example, we consider the sachdev-ye-kitaev (syk) model, which consists of spin-polarized fermions with an all-to-all complex random two-body hopping and has been conjectured to be dual to a certain quantum-gravitational system. achieving low-temperature states of the syk model is interpreted as a realization of a stringy black hole, provided that the holographic duality is true. we introduce a variant of the syk model, in which the random two-body hopping is real. this model is equivalent to the original syk model in the large-n limit. we show that this model can be created in principle by confining ultracold fermionic atoms into optical lattices and coupling two atoms with molecular states via photo-association lasers. this development serves as an important first step towards an experimental realization of such systems dual to quantum black holes. we also show how to measure out-of-time-order correlation functions of the syk model, which allow for identifying the maximally chaotic property of the black hole. | creating and probing the sachdev-ye-kitaev model with ultracold gases: towards experimental studies of quantum gravity |
when the bulk geometry in ads/cft contains a black hole, boundary subregions may be sufficient to reconstruct certain bulk operators if and only if the black hole microstate is known, an example of state dependence. reconstructions exist for any microstate, but no reconstruction works for all microstates. we refine this dichotomy, demonstrating that the same boundary operator can often be used for large subspaces of black hole microstates, corresponding to a constant fraction α of the black hole entropy. in the schrödinger picture, the boundary subregion encodes the α-bits (a concept from quantum information) of a bulk region containing the black hole and bounded by extremal surfaces. these results have important consequences for the structure of ads/cft and for quantum information. firstly, they imply that the bulk reconstruction is necessarily only approximate and allow us to place non-perturbative lower bounds on the error when doing so. second, they provide a simple and tractable limit in which the entanglement wedge is state dependent, but in a highly controlled way. although the state dependence of operators comes from ordinary quantum error correction, there are clear connections to the papadodimas-raju proposal for understanding operators behind black hole horizons. in tensor network toy models of ads/cft, we see how state dependence arises from the bulk operator being `pushed' through the black hole itself. finally, we show that black holes provide the first `explicit' examples of capacity-achieving α-bit codes. unintuitively, hawking radiation always reveals the α-bits of a black hole as soon as possible. in an appendix, we apply a result from the quantum information literature to prove that entanglement wedge reconstruction can be made exact to all orders in 1/n. | learning the alpha-bits of black holes |
we construct the holographic dictionary for both running and constant dilaton solutions of the two dimensional einstein-maxwell-dilaton theory that is obtained by a circle reduction from einstein-hilbert gravity with negative cosmological constant in three dimensions. this specific model ensures that the dual theory has a well defined ultraviolet completion in terms of a two dimensional conformal field theory, but our results apply qualitatively to a wider class of two dimensional dilaton gravity theories. for each type of solutions we perform holographic renormalization, compute the exact renormalized one-point functions in the presence of arbitrary sources, and derive the asymptotic symmetries and the corresponding conserved charges. in both cases we find that the scalar operator dual to the dilaton plays a crucial role in the description of the dynamics. its source gives rise to a matter conformal anomaly for the running dilaton solutions, while its expectation value is the only non trivial observable for constant dilaton solutions. the role of this operator has been largely overlooked in the literature. we further show that the only non trivial conserved charges for running dilaton solutions are the mass and the electric charge, while for constant dilaton solutions only the electric charge is non zero. however, by uplifting the solutions to three dimensions we show that constant dilaton solutions can support non trivial extended symmetry algebras, including the one found by compère, song and strominger [1], in agreement with the results of castro and song [2]. finally, we demonstrate that any solution of this specific dilaton gravity model can be uplifted to a family of asymptotically ads2 × s 2 or conformally ads2 × s 2 solutions of the stu model in four dimensions, including non extremal black holes. the four dimensional solutions obtained by uplifting the running dilaton solutions coincide with the so called `subtracted geometries', while those obtained from the uplift of the constant dilaton ones are new. | ads2 holographic dictionary |
we revisit the recent debate on the evidence for an overtone in the black hole ringdown of gw150914. by gating and inpainting the data, we discard the contamination from earlier parts of the gravitational wave signal before ringdown. this enables the parameter estimation to be conducted in the frequency domain, which is mathematically equivalent to the time domain method. we keep the settings as similar as possible to the previous studies by \textcite{cotesta:2022pci} and isi \textit{et al.}\cite{isi:2019aib,isi:2022mhy} which yielded conflicting results on the bayes factor of the overtone. we examine the spectral contents of the matched-filtering in the frequency domain, and propose a convergence test to assess the validity of an overtone model. our results find the bayes factors for the overtone fall within $10$ and $26$ around a range of times centered at the best-fit merger time of gw150914, which supports the existence of an overtone in agreement with the conclusions of isi \textit{et al.}\cite{isi:2019aib,isi:2022mhy}. our work contributes to the understanding of how various methods affect the statistical significance of overtones. | a frequency-domain perspective on gw150914 ringdown overtone |
the purpose of this chapter is to provide an overview of the exciting field of black hole quasi-normal modes and its capabilities to test general relativity in the 21st century. after motivating this line of research, we provide a qualitative introduction to the concept of quasi-normal modes and outline black hole perturbation theory. with the perturbation equations at hand, we discuss common methods to compute the quasi-normal mode spectrum and compare the advantages and disadvantages of each approach. we also provide an overview of possible deviations from general relativity and how they modify the quasi-normal mode spectrum of black holes from a theoretical point of view. we then review the rapidly evolving status of currently operating gravitational wave observatories and experimental results. the chapter concludes with a discussion of open problems and promising outlooks to theoretical and experimental developments. central pieces that make this chapter particularly interesting, also for advanced readers, are comprehensive tables providing a detailed overview of the status of techniques to compute quasi-normal modes and methods to describe quasi-normal modes of rotating black holes beyond general relativity. | testing general relativity with black hole quasi-normal modes |
recent developments have indicated that in addition to out-of-time ordered correlation functions (otocs), quantum chaos also has a sharp manifestation in the thermal energy density two-point functions, at least for maximally chaotic systems. the manifestation, referred to as pole-skipping, concerns the analytic behaviour of energy density two-point functions around a special point ω = iλ, k = iλ/vbin the complex frequency and momentum plane. here λ and vbare the lyapunov exponent and butterfly velocity characterising quantum chaos. in this paper we provide an argument that the phenomenon of pole-skipping is universal for general finite temperature systems dual to einstein gravity coupled to matter. in doing so we uncover a surprising universal feature of the linearised einstein equations around a static black hole geometry. we also study analytically a holographic axion model where all of the features of our general argument as well as the pole-skipping phenomenon can be verified in detail. | many-body chaos and energy dynamics in holography |
the bps sector in duality has been fertile ground for the exploration of gauge/gravity duality, from the match between black hole entropy and the cft elliptic genus to the construction of large families of geometrical microstates and the identification of the corresponding states in the cft. worldsheet methods provide a tool to further explore the relation between string theory in the bulk and corresponding cft quantities. we show how to match individual bps strings to their counterparts in the symmetric product orbifold cft. in the process, we find an exact match between known constructions of microstate geometries and condensates of bps supergraviton strings, and discuss their role in the broader collection of bps states. in particular, we explore how microstate geometries develop singularities; and how string theory resolves these singularities through the appearance of "tensionless" string dynamics, which is the continuation of structures found in the weak-coupling cft into the strongly coupled regime described by string theory in the bulk. we argue that such "tensionless" strings are responsible for black hole microstructure in the bulk description.the bps sector in duality has been fertile ground for the exploration of gauge/gravity duality, from the match between black hole entropy and the cft elliptic genus to the construction of large families of geometrical microstates and the identification of the corresponding states in the cft. worldsheet methods provide a tool to further explore the relation between string theory in the bulk and corresponding cft quantities. we show how to match individual bps strings to their counterparts in the symmetric product orbifold cft. in the process, we find an exact match between known constructions of microstate geometries and condensates of bps supergraviton strings, and discuss their role in the broader collection of bps states. in particular, we explore how microstate geometries develop singularities; and how string theory resolves these singularities through the appearance of "tensionless" string dynamics, which is the continuation of structures found in the weak-coupling cft into the strongly coupled regime described by string theory in the bulk. we argue that such "tensionless" strings are responsible for black hole microstructure in the bulk description. | on the bps sector in ads 3 /cft 2 holography |
we review recent developments in jackiw-teitelboim gravity. this is a simple solvable model of quantum gravity in two dimensions (that arises e.g. from the s-wave sector of higher dimensional gravity systems with spherical symmetry). due to its solvability, it has proven to be a fruitful toy model to analyze important questions such as the relation between black holes and chaos, the role of wormholes in black hole physics and holography, and the way in which information that falls into a black hole can be recovered. | solvable models of quantum black holes: a review on jackiw-teitelboim gravity |
black holes drive powerful plasma jets to relativistic velocities. this plasma should be collisionless, and self-consistently supplied by pair creation near the horizon. we present general-relativistic collisionless plasma simulations of kerr-black-hole magnetospheres which begin from vacuum, inject e± pairs based on local unscreened electric fields, and reach steady states with electromagnetically powered blandford-znajek jets and persistent current sheets. particles with negative energy at infinity are a general feature, and can contribute significantly to black-hole rotational-energy extraction in a variant of the penrose process. the generated plasma distribution depends on the pair-creation environment, and we describe two distinct realizations of the force-free electrodynamic solution. this sensitivity suggests that plasma kinetics will be useful in interpreting future horizon-resolving submillimeter and infrared observations. | first-principles plasma simulations of black-hole jet launching |
the origin of black hole mergers discovered by the ligo1 and virgo2 gravitational-wave observatories is currently unknown. gw1905213,4 is the heaviest black hole merger detected so far. its observed high mass and possible spin-induced orbital precession could arise from the binary having formed following a close encounter. an observational signature of close encounters is eccentric binary orbit5-7; however, this feature is currently difficult to identify due to the lack of suitable gravitational waveforms. no eccentric merger has been previously found8. here we report 611 numerical relativity simulations covering the full eccentricity range and an estimation approach to probe the eccentricity of mergers. our set of simulations corresponds to ~105 waveforms, comparable to the number used in gravitational-wave searches, albeit with coarser mass ratio and spin resolution. we applied our approach to gw190521 and found that it is most consistent with a highly eccentric (e =0.6 9−0.22+0.17 ; 90% credible level) merger within our set of waveforms. this interpretation is supported over a non-eccentric merger with >10 odds ratio if ≳10% of gw190521-like mergers are highly eccentric. detectable orbital eccentricity would be evidence against an isolated binary origin, which is otherwise difficult to rule out on the basis of observed mass and spin9,10. | eccentricity estimate for black hole mergers with numerical relativity simulations |
in this paper, we extend our previous work [d. wu, phys. rev. d 107, 024024 (2023), 10.1103/physrevd.107.024024] to the more general cases with a negative cosmological constant, and investigate the topological numbers for the singly rotating kerr-ads black holes in all dimensions and the four-dimensional kerr-newman-ads black hole as well as the three-dimensional bañados-teitelboim-zanelli black hole. we find that the topological numbers of black holes are remarkably influenced by the cosmological constant. in addition, we also demonstrate that the dimension of spacetimes has an important effect on the topological number for rotating anti-de sitter (ads) black holes. furthermore, it is interesting to observe that the difference between the topological number of the ads black hole and that of its corresponding asymptotically flat black hole is always unity. this new observation leads us to conjure that it might be valid also for other black holes. of course, this novel conjecture needs to be further verified by examining the topological numbers of many other black holes and their ads counterparts in the future work. | topological classes of thermodynamics of rotating ads black holes |
we provide a detailed examination of a thermal out-of-time-order correlator (otoc) growing exponentially in time in systems without chaos. the system is a one-dimensional quantum mechanics with a potential whose part is an inverted harmonic oscillator. we numerically observe the exponential growth of the otoc when the temperature is higher than a certain threshold. the lyapunov exponent is found to be of the order of the classical lyapunov exponent generated at the hilltop, and it remains non-vanishing even at high temperature. we adopt various shape of the potential and find these features universal. the study confirms that the exponential growth of the thermal otoc does not necessarily mean chaos when the potential includes a local maximum. we also provide a bound for the lyapunov exponent of the thermal otoc in generic quantum mechanics in one dimension, which is of the same form as the chaos bound obtained by maldacena, shenker and stanford. | exponential growth of out-of-time-order correlator without chaos: inverted harmonic oscillator |
we apply the hilbert series to extend the gravitational action for a scalar field to a complete, non-redundant basis of higher-dimensional operators that is quadratic in the scalars and the weyl tensor. such an extension of the action fully describes tidal effects arising from operators involving two powers of the curvature. as an application of this new action, we compute all spinless tidal effects at the leading post-minkowskian order. this computation is greatly simplified by appealing to the heavy limit, where only a severely constrained set of operators can contribute classically at the one-loop level. finally, we use this amplitude to derive the o (g2) tidal corrections to the hamiltonian and the scattering angle. | tidal effects in quantum field theory |
we discuss holographic models of extremal and non-extremal black holes in contact with a bath in d dimensions, based on a brane world model introduced in [1]. the main benefit of our setup is that it allows for a high degree of analytic control as compared to previous work in higher dimensions. we show that the appearance of quantum extremal islands in those models is a consequence of the well-understood phase transition of rt surfaces, and does not make any direct reference to ensemble averaging. for non-extremal black holes the appearance of quantum extremal islands has the right behaviour to avoid the information paradox in any dimension. we further show that for these models the calculation of the full page curve is possible in any dimension. the calculation reduces to numerically solving two odes. in the case of extremal black holes in higher dimensions, we find no quantum extremal islands for a wide range of parameters. in two dimensions, our results agree with [2] at leading order; however a finite uv cutoff introduced by the brane results in subleading corrections. for example, these corrections result in the quantum extremal surfaces moving further outward from the horizon, and shifting the page transition to a slightly earlier time. | quantum extremal islands made easy. part ii. black holes on the brane |
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