Light rings as observational evidence for event horizons: Long-lived modes, ergoregions and nonlinear instabilities of ultracompact objects

Cardoso, Vítor; Crispino, Luís C. B.; Macedo, Caio F. B.; Okawa, Hirotada; Pani, Paolo

doi:10.1103/physrevd.90.044069

Cited by 251 publications

(333 citation statements)

References 52 publications

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“…We can compare this result with the behaviour of quasinormal modes for AdS black holes [28,29] or ultracompact stars [30]. There are two important differences.…”

Section: Jhep10(2016)031mentioning

confidence: 92%

Instability of supersymmetric microstate geometries

Eperon

Reall

Santos

2016

J. High Energ. Phys.

191

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Abstract:We investigate the classical stability of supersymmetric, asymptotically flat, microstate geometries with five non-compact dimensions. Such geometries admit an "evanescent ergosurface": a timelike hypersurface of infinite redshift. On such a surface, there are null geodesics with zero energy relative to infinity. These geodesics are stably trapped in the potential well near the ergosurface. We present a heuristic argument indicating that this feature is likely to lead to a nonlinear instability of these solutions. We argue that the precursor of such an instability can be seen in the behaviour of linear perturbations: nonlinear stability would require that all linear perturbations decay sufficiently rapidly but the stable trapping implies that some linear perturbation decay very slowly. We study this in detail for the most symmetric microstate geometries. By constructing quasinormal modes of these geometries we show that generic linear perturbations decay slower than any inverse power of time.

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“…We can compare this result with the behaviour of quasinormal modes for AdS black holes [28,29] or ultracompact stars [30]. There are two important differences.…”

Section: Jhep10(2016)031mentioning

confidence: 92%

Instability of supersymmetric microstate geometries

Eperon

Reall

Santos

2016

J. High Energ. Phys.

191

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“…Note that most unperturbed solutions we consider have their radius of R/M < 3. Such solutions might be nonlinearly unstable as pointed out in [17,18].…”

Section: Thin Shell Gravastar In the Zero-rotation Limitmentioning

confidence: 94%

Slowly rotating thin shell gravastars

Uchikata

Yoshida

2015

Class. Quantum Grav.

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Abstract. We construct the solutions of slowly rotating gravastars with a thin shell. In the zero-rotation limit, we consider the gravastar composed of a de Sitter core, a thin shell, and Schwarzschild exterior spacetime. The rotational effects are treated as small axisymmetric and stationary perturbations. The perturbed internal and external spacetimes are matched with a uniformly rotating thin shell. We assume that the angular velocity of the thin shell, Ω, is much smaller than the Keplerian frequency of the nonrotating gravastar, Ω k . The solutions within an accuracy up to the second order of Ω/Ω k are obtained. The thin shell matter is assumed to be described by a perfect fluid and to satisfy the dominant energy condition in the zero-rotation limit. In this study, we assume that the equation of state for perturbations is the same as that of the unperturbed solution. The spherically symmetric component of the energy density perturbations, δσ 0 , is assumed to vanish independently of the rotation rate. Based on these assumptions, we obtain many numerical solutions and investigate properties of the rotational corrections to the structure of the thin shell gravastar.

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“…We will not discuss specific models, but we would like to highlight two general results. Linearized gravitational fluctuations of any nonspinning UCO are extremely long-lived and decay no faster than logarithmically [56,112,113,141]. Indeed, such perturbations can be again understood in terms of modes quasi-trapped within the potential barrier shown in Fig.…”

Section: On the Stability Problemmentioning

confidence: 98%

Tests for the existence of black holes through gravitational wave echoes

2017

Self Cite

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The existence of black holes and of spacetime singularities is a fundamental issue in science. Despite this, observations supporting their existence are scarce, and their interpretation unclear. We overview how strong a case for black holes has been made in the last few decades, and how well observations adjust to this paradigm. Unsurprisingly, we conclude that observational proof for black holes is impossible to come by. 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 next few years and decades, we will enter the era of precision gravitational-wave physics with more sensitive detectors. Just as accelerators require larger and larger energies to probe smaller and smaller scales, more sensitive gravitational-wave detectors will be probing regions closer and closer to the horizon, potentially reaching Planck scales and beyond. What may be there, lurking? 1 arXiv:1707.03021v4 [gr-qc]

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Light rings as observational evidence for event horizons: Long-lived modes, ergoregions and nonlinear instabilities of ultracompact objects

Cited by 251 publications

References 52 publications

Instability of supersymmetric microstate geometries

Instability of supersymmetric microstate geometries

Slowly rotating thin shell gravastars

Tests for the existence of black holes through gravitational wave echoes

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