The multipolar structure of fuzzballs

Bianchi, Massimo; Consoli, Dario; Grillo, Alfredo; Morales, José F.; Pani, Paolo; Raposo, Guilherme

doi:10.1007/jhep01(2021)003

Cited by 58 publications

(91 citation statements)

References 67 publications

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“…• When δ micro is finite, the microstate-dependent contribution proportional to O (δ micro ) can modify the classical-black-hole result. In particular, in [17,19] an analysis of certain families of microstate geometries suggested that microstate geometries have bigger multipoles than the black hole with the same charges, implying that perhaps the black hole is an extremum in the phase space of solutions for certain observables. 5 We have constructed a number of almost-BPS microstate geometries that show explicitly that the black hole is not an extremum in solution phase space, at least not as far as multipoles are concerned.…”

Section: Summary Of Our Resultsmentioning

confidence: 99%

“…4 We show that the deviations are rather "random" as they depend on the geometry of the topologically non-trivial bubbles that give the horizon-scale structure, and they can be either positive or negative; this is in contrast with the analysis of [17], where the multipoles of certain microstate geometries were found to be larger than the multipoles of their corresponding black holes. In a broader scope, our constructions and studies in this paper allow us to understand the physics of potential microstructure of the Kerr black hole much better than what one could hope from naively extrapolating the supersymmetric microstate results as was previously done in [16][17][18][19].…”

Section: Jhep10(2021)138mentioning

confidence: 90%

“…There are regularity conditions (see (C. 19)) that the geometry must satisfy, as well as the condition to be asymptotic to flat four-dimensional spacetime; together, these give 5 algebraic conditions. Three directly fix 0 , m ∞ and m (0) ; the other are called bubble equations and are non-linear relations that constrain the distances between the centers:…”

Section: Jhep10(2021)138mentioning

confidence: 99%

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Gravitational footprints of black holes and their microstate geometries

Bah

Bena

Heidmann

et al. 2021

J. High Energ. Phys.

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We construct a family of non-supersymmetric extremal black holes and their horizonless microstate geometries in four dimensions. The black holes can have finite angular momentum and an arbitrary charge-to-mass ratio, unlike their supersymmetric cousins. These features make them and their microstate geometries astrophysically relevant. Thus, they provide interesting prototypes to study deviations from Kerr solutions caused by new horizon-scale physics. In this paper, we compute the gravitational multipole structure of these solutions and compare them to Kerr black holes. The multipoles of the black hole differ significantly from Kerr as they depend non-trivially on the charge-to-mass ratio. The horizonless microstate geometries (that are comparable in size to a black hole) have a similar multipole structure as their corresponding black hole, with deviations to the black hole multipole values set by the scale of their microstructure.

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Section: Summary Of Our Resultsmentioning

confidence: 99%

Section: Jhep10(2021)138mentioning

confidence: 90%

Section: Jhep10(2021)138mentioning

confidence: 99%

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Gravitational footprints of black holes and their microstate geometries

Bah

Bena

Heidmann

et al. 2021

J. High Energ. Phys.

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“…moments (see [43][44][45][46] for recent developments in this direction, and [47] for a nice review on the subject) and the QNM's that we plan to analyse in the near future. in this respect, it is worth recalling that the Lyapunov exponent λ sets the scale of the imaginary part of ω QNM , thus motivating our detailed analysis of near critical null geodesics in the vicinity of the photon-sphere.…”

Section: Jhep03(2021)210mentioning

confidence: 99%

Light rings of five-dimensional geometries

Bianchi

Consoli

Grillo

et al. 2021

J. High Energ. Phys.

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We study massless geodesics near the photon-spheres of a large family of solutions of Einstein-Maxwell theory in five dimensions, including BHs, naked singularities and smooth horizon-less JMaRT geometries obtained as six-dimensional uplifts of the five-dimensional solution. We find that a light ring of unstable photon orbits surrounding the mass center is always present, independently of the existence of a horizon or singularity. We compute the Lyapunov exponent, characterizing the chaotic behaviour of geodesics near the ‘photon-sphere’ and the time decay of ring-down modes dominating the response of the geometry to perturbations at late times. We show that, for geometries free of naked singularities, the Lyapunov exponent is always bounded by its value for a Schwarzschild BH of the same mass.

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“…Besides, quantum gravity may play an important role both inside and outside horizons of black holes in order to resolve the so-called information paradox [4][5][6][7]. It has been proposed that spacetime geometry near the horizon can be modified, even at scales larger than the Planck scale [5][6][7][8][9][10][11][12][13][14][15][16][17]. It has also been conjectured that a phase transition might occur during the formation of black holes, leading to nonsingular, yet extremely compact objects [18,19].…”

Section: Introductionmentioning

confidence: 99%

Tidal response and near-horizon boundary conditions for spinning exotic compact objects

2021

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Teukolsky equations for jsj ¼ 2 provide efficient ways to solve for curvature perturbations around Kerr black holes. Imposing regularity conditions on these perturbations on the future (past) horizon corresponds to imposing an ingoing (outgoing) wave boundary condition. For exotic compact objects (ECOs) with external Kerr spacetime, however, it is not yet clear how to physically impose boundary conditions for curvature perturbations on their boundaries. We address this problem using the membrane paradigm, by considering a family of zero-angular-momentum fiducial observers (FIDOs) that float right above the horizon of a linearly perturbed Kerr black hole. From the reference frame of these observers, the ECO will experience tidal perturbations due to ingoing gravitational waves, respond to these waves, and generate outgoing waves. As it also turns out, if both ingoing and outgoing waves exist near the horizon, the Newman-Penrose (NP) quantity ψ 0 will be numerically dominated by the ingoing wave, while the NP quantity ψ 4 will be dominated by the outgoing wave-even though both quantities contain full information regarding the wave field. In this way, we obtain the ECO boundary condition in the form of a relation between ψ 0 and the complex conjugate of ψ 4 , in a way that is determined by the ECO's tidal response in the FIDO frame. We explore several ways to modify gravitational-wave dispersion in the FIDO frame and deduce the corresponding ECO boundary condition for Teukolsky functions. Using the Starobinsky-Teukolsky identity, we subsequently obtain the boundary condition for ψ 4 alone, as well as for the Sasaki-Nakamura and Detweiler functions. As it also turns out, the reflection of spinning ECOs will generically mix between different l components of the perturbation fields, and it will be different for perturbations with different parities. It is straightforward to apply our boundary condition to computing gravitational-wave echoes from spinning ECOs, and to solve for the spinning ECOs' quasinormal modes.

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The multipolar structure of fuzzballs

Cited by 58 publications

References 67 publications

Gravitational footprints of black holes and their microstate geometries

Gravitational footprints of black holes and their microstate geometries

Light rings of five-dimensional geometries

Tidal response and near-horizon boundary conditions for spinning exotic compact objects

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