Related papers: Instability of hyper-compact Kerr-like objects
A co-rotating bosonic field interacting with a spinning Kerr black hole can extract rotational energy and angular momentum from the hole. This intriguing phenomenon is known as superradiant scattering. As pointed out by Press and Teukolsky,…
We investigate the stability of higher dimensional rotating black holes against scalar perturbations. In particular, we make a thorough numerical and analytical analysis of six-dimensional black holes, not only in the low rotation regime…
We analytically study the linear response of a near-extremal Kerr black hole to external scalar, electromagnetic, and gravitational field perturbations. We show that the energy density, electromagnetic field strength, and tidal force…
We use the data of several promising gravitational wave observations to obtain increasingly stringent bounds on near-horizon deviations of their sources from the Kerr geometry. A range of horizonless compact objects proposed as alternatives…
Sun-like stars can transmute into comparable mass black holes by steadily accumulating heavy non-annihilating dark matter particles over the course of their lives. If such stars form in binary systems, they could give rise to…
We study r-mode instability of rotating compact objects composed of asymmetric and self-interacting Fermionic dark matter (dark stars). It is argued that the instability limit the angular frequency of the stars less than half of the…
A number of authors provided arguments that a rotating gravastar is a good candidate for a source of the Kerr metric. These arguments were based on the second order perturbation analysis. In the following paper, we construct a perturbative…
We perform the first nonlinear and self-consistent study of the merger and ringdown of a black hole mimicking object with stable light rings. To that end, we numerically solve the full Einstein-Klein-Gordon equations governing the head-on…
Spherically symmetric bosonic stars are one of the few examples of gravitating solitons that are known to form dynamically, via a classical process of (incomplete) gravitational collapse. As stationary solutions of the…
Boson stars have attracted much attention in recent decades as simple, self-consistent models of compact objects and also as self-gravitating structures formed in some dark-matter scenarios. Direct detection of these hypothetical objects…
We demonstrate that black holes and stars in general relativity can be destabilized by perturbations of non-minimally coupled vector fields. Focusing on static and spherically symmetric backgrounds, our analysis shows that black holes with…
We consider linear gravitational perturbations of the Kerr brane, an exact solution of vacuum Einstein's equations in dimensions higher than four and a low-energy solution of string theory. Decomposing the perturbations in tensor harmonics…
The general equations describing hydrostatic equilibrium are developed for Non-singular Gravity. A new type of astrophysical structure, a Super Dense Object (SDO) or "Dark Star", is shown to exist beyond Neutron star field strengths. These…
Recent non-modal analyses have uncovered spectral instabilities in the quasinormal-mode spectrum of black holes; a phenomenon that intriguingly extends to spherically-symmetric exotic compact objects. These results point to a sensitivity of…
Gravastars have been recently proposed as potential alternatives to explain the astrophysical phenomenology traditionally associated to black holes, raising the question of whether the two objects can be distinguished at all. Leaving aside…
A (charged) rotating black hole may be unstable against a (charged) massive scalar field perturbation due to the existence of superradiance modes. The stability property depends on the parameters of the system. In this paper, the…
A number of theoretical proposals have been made for horizonless compact objects with masses and spins similar to those of black holes. While gravitational wave signatures from their mergers can resemble those of black holes, features like…
Due to coherent superradiant amplification, massive bosonic fields can trigger an instability in spinning black holes, tapping their energy and angular momentum and forming macroscopic Bose-Einstein condensates around them. This phenomenon…
The visual distortion effects visible to an observer traveling around and descending to the surface of an extremely compact star are described. Specifically, trips to a ``normal" neutron star, a black hole, and an ultracompact neutron star…
Topological stars are regular, horizonless solitons arising from dimensional compactification of Einstein-Maxwell theory in five dimensions, which could describe qualitative properties of microstate geometries for astrophysical black holes.…