We present fully general relativistic simulations of the quasicircular inspiral and merger of charged, nonspinning, binary black holes with chargetomass ratio λ≤0.3. We discuss the key features that enabled long term and stable evolutions of these binaries. We also present a formalism for computing the angular momentum carried away by electromagnetic waves, and the electromagnetic contribution to blackhole horizon properties. We implement our formalism and present the results for the first time in numericalrelativity simulations. In addition, we compare our full nonlinear solutions with existing approximate models for the inspiral and ringdown phases. We show that Newtonian models based on the quadrupole approximation have errors of 20 %  100 % in key gaugeinvariant quantities. On the other hand, for the systems considered, we find that estimates of the remnant black hole spin based on the motion of test particles in KerrNewman spacetimes agree with our nonlinear calculations to within a few percent. Finally, we discuss the prospects for detecting black hole charge by future gravitationalwave detectors using either the inspiralmergerringdown signal or the ringdown signal alone.
This content will become publicly available on January 1, 2023
Extremal black holes that are not extremal: maximal warm holes
A bstract We study a family of fourdimensional, asymptotically flat, charged black holes that develop (charged) scalar hair as one increases their charge at fixed mass. Surprisingly, the maximum charge for given mass is a nonsingular hairy black hole with nonzero Hawking temperature. The implications for Hawking evaporation are discussed.
 Award ID(s):
 2107939
 Publication Date:
 NSFPAR ID:
 10322657
 Journal Name:
 Journal of High Energy Physics
 Volume:
 2022
 Issue:
 1
 ISSN:
 10298479
 Sponsoring Org:
 National Science Foundation
More Like this


Abstract Nontrivial diffeomorphisms act on the horizon of a generic 4D black holes and create distinguishing features referred to as soft hair. Amongst these are a left–right pair of Virasoro algebras with associated charges that reproduce the Bekenstein–Hawking entropy for Kerr black holes. In this paper we show that if one adds a negative cosmological constant, there is a similar set of infinitesimal diffeomorphisms that act nontrivially on the horizon. The algebra of these diffeomorphisms gives rise to a central charge. Adding a boundary counterterm, justified to achieve integrability, leads to welldefined central charges with c L = c R . The macroscopic area law for KerrAdS black holes follows from the assumption of a Cardy formula governing the black hole microstates.

Abstract Due to the failure of thermodynamics for low temperature nearextremal black holes, it has long been conjectured that a ‘thermodynamic mass gap’ exists between an extremal black hole and the lightest nearextremal state. For nonsupersymmetric nearextremal 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 nonperturbative corrections. In this paper, we compute the partition function of nearBPS black holes in supergravity where the emergent, broken, symmetry is PSU (1, 12). To reliably compute this partition function, we show that the gravitational path integral can be reduced to that of a N = 4 supersymmetric extension of the Schwarzian theory, which we define and exactly quantize. In contrast to the nonsupersymmetric 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 a plethora of string theory conjectures, concerning the scale of the mass gap and the counting of extremal microstates.

A bstract As a black hole evaporates, each outgoing Hawking quantum carries away some of the black holes asymptotic charges associated with the extended BondiMetznerSachs group. These include the Poincaré charges of energy, linear momentum, intrinsic angular momentum, and orbital angular momentum or centerofmass charge, as well as extensions of these quantities associated with supertranslations and superLorentz transformations, namely supermomentum, superspin and super centerofmass charges (also known as soft hair). Since each emitted quantum has fluctuations that are of order unity, fluctuations in the black hole’s charges grow over the course of the evaporation. We estimate the scale of these fluctuations using a simple model. The results are, in Planck units: (i) The black hole position has a uncertainty of $$ \sim {M}_i^2 $$ ∼ M i 2 at late times, where M i is the initial mass (previously found by Page). (ii) The black hole mass M has an uncertainty of order the mass M itself at the epoch when M ∼ $$ {M}_i^{2/3} $$ M i 2 / 3 , well before the Planck scale is reached. Correspondingly, the time at which the evaporation ends has an uncertainty of order $$ \sim {M}_i^2 $$ ∼ M i 2more »

A bstract In twoderivative theories of gravity coupled to matter, charged black holes are selfattractive at large distances, with the force vanishing at zero temperature. However, in the presence of massless scalar fields and fourderivative corrections, zerotemperature black holes no longer need to obey the noforce condition. In this paper, we show how to calculate the longrange force between such black holes. We develop an efficient method for computing the higherderivative corrections to the scalar charges when the theory has a shift symmetry, and compute the resulting force in a variety of examples. We find that higherderivative corrected black holes may be selfattractive or selfrepulsive, depending on the value of the Wilson coefficients and the VEVs of scalar moduli. Indeed, we find black hole solutions which are both superextremal and selfattractive. Furthermore, we present examples where no choice of higherderivative coefficients allows for selfrepulsive black hole states in all directions in charge space. This suggests that, unlike the Weak Gravity Conjecture, which may be satisfied by the black hole spectrum alone, the Repulsive Force Conjecture requires additional constraints on the spectrum of charged particles.