相关论文: Pair creation in non-extremal fuzzball geometries

We study properties of particles with zero or negative energy and a nonzero orbital angular momentum in the ergosphere of a rotating black hole. We show that the sign of the particle energy is uniquely determined by the angular velocity of…

Hawking particles emitted by a black hole are usually found to have thermal spectra, if not exactly, then by a very good approximation. Here, we argue differently. It was discovered that spherical partial waves of in-going and out-going…

We show that the gravitational quasi-normal modes (QNMs) of a Schwarzschild black hole play the role of a multimode squeezer that can generate particles. For a minimally coupled scalar field, the QNMs "squeeze" the initial state of the…

Semiclassical black holes emit radiation called Hawking radiation. Such radiation, as seen by an asymptotic observer far outside the black hole, differs from original radiation near the horizon of the black hole by a redshift factor and the…

Black holes play a fundamental role in modern physics. They have characteristic oscillation modes, called quasinormal modes. Past studies have shown that these modes are important to our understanding of the dynamics of astrophysical black…

Superradiance, the phenomenon enabling energy extraction through radiation amplification, is not universal to all black holes. We show that semi-classical backreaction can induce superradiance, even when absent at the classical level.…

The black hole information paradox is one of the most important issues in theoretical physics. We review some recent progress using string theory in understanding the nature of black hole microstates. For all cases where these microstates…

The ergoregion instability is known to affect very compact objects that rotate very rapidly and do not possess a horizon. We present here a detailed analysis on the relevance of the ergoregion instability for the viability of gravastars.…

Most of the properties of black holes can be mimicked by horizonless compact objects such as gravastars and boson stars. We show that these ultra-compact objects develop a strong ergoregion instability when rapidly spinning. Instability…

We provide a new roadmap for constructing microstates of non-extremal black holes in supergravity. First, we review the non-linear sigma model of five-dimensional supergravity governing stationary solutions with a U(1) isometry and present…

Black holes (BHs) play a central role in physics. However, gathering observational evidence for their existence is a notoriously difficult task. Current strategies to quantify the evidence for BHs all boil down to looking for signs of…

Active galactic nuclei often exhibit highly collimated relativistic plasma outflows launched from the vicinity of their central black holes. One of the key theoretical challenges in understanding black hole jet formation is the origin of…

In a recent publication, we have demonstrated that differentially rotating stars admit new channels of black hole formation via fragmentation instabilities. Since a higher order instability of this kind could potentially transform a…

We study the thermodynamical properties of black holes when described as gases of indistinguishable punctures with a chemical potential. In this picture, which arises from loop quantum gravity, the black hole microstates are defined by…

An introduction is given to a meeting on the role of massive and stellar black holes in powering non-thermal activity in a rich variety of cosmic sources. Relevant properties of magnetized, spinning black holes are summarized and their…

Dynamical models of prototype gravastars made of phantom energy are constructed, in which an infinitely thin spherical shell of a perfect fluid with the equation of state $p = (1-\gamma)\sigma$ divides the whole spacetime into two regions,…

According to a variant of the hoop conjecture, if we localize two particles within the Schwarzschild radius corresponding to their center of mass energy, then a black hole will form. Despite a large body of work on the formation of…

We study the possibility of the Primordial Black Holes (PBHs) formation with the aim of finding a considerable fraction of Dark Matter (DM), using the gravitationally enhanced friction mechanism which arises from a nonminimal derivative…

Emission of particles created in the background of a rotating black hole can be greatly amplified taking away rotational energy of a black hole. This amplification affects both particles created near the horizon (due to the Hawing effect),…

We investigate the quantum dynamics of a charged scalar field in the near-horizon region of a near-extremal charged BTZ black hole. A controlled expansion of the Einstein-Maxwell equations reveals an emergent warped AdS$_2 \times S^1$…