Ultra-spinning exotic compact objects supporting static massless scalar field configurations

Abstract

Horizonless spacetimes describing highly compact exotic objects with reflecting (instead of absorbing) surfaces have recently attracted much attention from physicists and mathematicians as possible quantum-gravity alternatives to canonical classical black-hole spacetimes. Interestingly, it has recently been proved that spinning compact objects with angular momenta in the sub-critical regime $\bar{a}\equiv J/M^2\le 1$ are characterized by an infinite countable set of surface radii, $\{r_{\text{c}}(\bar{a};n){\}}_{n=1}^{n=\infty }$, that can support asymptotically flat static configurations made of massless scalar fields. In the present paper we study analytically the physical properties of ultra-spinning exotic compact objects with dimensionless angular momenta in the complementary regime $\bar{a}>1$. It is proved that ultra-spinning reflecting compact objects with dimensionless angular momenta in the super-critical regime $\sqrt{1-[m/(l+2){]}^2}\le |\bar{a}{|}^{-1}<1$ are characterized by a finite discrete family of surface radii, $\{r_{\text{c}}(\bar{a};n){\}}_{n=1}^{n=N_{\text{r}}}$, distributed symmetrically around $r=M$, that can support spatially regular static configurations of massless scalar fields (here the integers $\{l,m\}$ are the harmonic indices of the supported static scalar field modes). Interestingly, the largest supporting surface radius $r_{\text{c}}^{\text{max}}(\bar{a})\equiv {\text{max}}_n\{r_{\text{c}}(\bar{a};n)\}$ marks the onset of superradiant instabilities in the composed ultra-spinning-exotic-compact-object-massless-scalar-field system.

13 pages

References in corpus (47)

• Observation of Gravitational Waves from a Binary Black Hole Merger
• GW151226: Observation of Gravitational Waves from a 22-Solar-Mass Binary Black Hole Coalescence
• The fuzzball proposal for black holes: an elementary review
• Kerr black holes with scalar hair
• Shadows of Kerr black holes with scalar hair
• The fuzzball proposal for black holes
• Light rings as observational evidence for event horizons: long-lived modes, ergoregions and nonlinear instabilities of ultracompact objects
• How to tell a gravastar from a black hole
• Superradiant Instability and Backreaction of Massive Vector Fields around Kerr Black Holes
• Kerr black holes with Proca hair
• Stationary Scalar Clouds Around Rotating Black Holes
• Gravitational wave signatures of the absence of an event horizon. I. Nonradial oscillations of a thin-shell gravastar
• Kerr-Newman scalar clouds
• Weak Cosmic Censorship: As Strong as Ever
• Stationary resonances of rapidly-rotating Kerr black holes
• Kerr-Newman black holes with stationary charged scalar clouds
• Kerr black holes with self-interacting scalar hair: hairier but not heavier
• On the instability regime of the rotating Kerr spacetime to massive scalar perturbations
• Did GW150914 produce a rotating gravastar?
• Classes of Exact Solutions to the Teukolsky Master Equation
• Tidal deformability and I-Love-Q relations for gravastars with polytropic thin shells
• A new spin on black hole hair
• Analytic treatment of the black-hole bomb
• I-Love-Q relations for a gravastar and the approach to the black-hole limit
• Non-linear Q-clouds around Kerr black holes
• Scalarized Hairy Black Holes
• Myers-Perry black holes with scalar hair and a mass gap
• I-Love-Q anisotropically: Universal relations for compact stars with scalar pressure anisotropy
• The large-mass limit of cloudy black holes
• Extremal Kerr-Newman black holes with extremely short charged scalar hair
• The superradiant instability regime of the spinning Kerr black hole
• Rotating black holes can have short bristles
• Inside black holes with synchronized hair
• Teukolsky-Starobinsky Identities - a Novel Derivation and Generalizations
• Myers-Perry black holes with scalar hair and a mass gap: unequal spins
• How fast can a black hole rotate?
• Spinning boson stars and Kerr black holes with scalar hair: the effect of self-interactions
• Wiggly tails: a gravitational wave signature of massive fields around black holes
• A no-short scalar hair theorem for rotating Kerr black holes
• No-scalar-hair theorem for spherically symmetric reflecting stars
• No-hair theorems for a static and stationary reflecting star
• No nonminimally coupled massless scalar hair for spherically symmetric neutral reflecting stars
• Onset of superradiant instabilities in rotating spacetimes of exotic compact objects
• Eigenvalue spectrum of the spheroidal harmonics: A uniform asymptotic analysis
• Stationary bound-state scalar configurations supported by rapidly-spinning exotic compact objects
• Asymptotic spectrum of the oblate spin-weighted spheroidal harmonics: a WKB analysis
• Black-hole perturbation theory: The asymptotic spectrum of the prolate spin-weighted spheroidal harmonics

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• On the instability of ultracompact horizonless spacetimes
• Isotropic compact stars in 4D Einstein-Gauss-Bonnet gravity
• Analytic study of self-gravitating polytropic spheres with light rings
• Lower bound on the compactness of isotropic ultra-compact objects
• Upper bound on the radii of regular ultra-compact star photonspheres
• Exotic compact object behavior in black hole analogues
• On instabilities of stationary scalar field configurations supported by reflecting compact stars