Related papers: Black Hole Portal into Hidden Valleys
Generic extensions of the standard model predict the existence of ultralight bosonic degrees of freedom. Several ongoing experiments are aimed at detecting these particles or constraining their mass range. Here we show that massive vector…
Black hole binary systems can emit very bright and rapidly varying X-ray signals when material from the companion accretes onto the black hole, liberating huge amounts of gravitational potential energy. Central to this process of accretion…
A recent understanding on how quantum effects may affect black-hole evolution opens new scenarios for dark matter, in connection with the presence of black holes in the very early universe. Quantum fluctuations of the geometry allow for…
Rotating black holes (BHs) can efficiently transfer energy to the surrounding environment via superradiance. In particular, when the Compton length of a particle is comparable to the gravitational radius of a BH, the particle's occupation…
Studies of black hole superradiance often focus on the growth of a cloud in isolation, accompanied by the spin-down of the black hole. In this paper, we consider the additional effect of the accretion of matter and angular momentum from the…
Superradiance is a radiation enhancement process that involves dissipative systems. With a 60 year-old history, superradiance has played a prominent role in optics, quantum mechanics and especially in relativity and astrophysics. In General…
Magnetic fields surrounding spinning black holes can confine radiation and trigger superradiant instabilities. To investigate this effect, we perform the first fully-consistent linear analysis of the Ernst spacetime, an exact solution of…
We show that electromagnetic excitations of rotating black holes can lead to the appearance of narrow singular beams which break up the black hole horizon forming a tube-like region which connects the interior and exterior. It is argued…
Electromagnetic field confinement due to plasma near accreting black holes can trigger superradiant instabilities at the linear level, limiting the spin of black holes and providing novel astrophysical sources of electromagnetic bursts.…
Some issues relevant for the formation of supermassive black holes are discused and estimates of the event rates for the emission of gravitational waves by coalescing supermassive black hole binaries are given. The models take into account…
The theory of coronal evaporation predicts the formation of an inner hole in the cool thin accretion disk for mass accretion rates below a certain value (~ 1/50 of the Eddington mass accretion rate) and the sudden disappearance of this hole…
We investigate the possibility of the acoustic superresonance phenomenon (analog to the superradiance in black hole physics), i.e., the amplification of a sound wave by reflection from the ergoregion of a rotating acoustic black hole with…
Most of the X-ray emission from luminous accreting black holes emerges from within 20 gravitational radii. The effective emission radius is several times smaller if the black hole is rapidly spinning. General Relativistic effects can then…
When a scalar wave perturbation is properly scattering off a charged or rotating black hole, the energy of the reflected scalar wave may be amplified. This is a superradiant process. If this amplification process can occur back and forth…
Tidal disruption events (TDEs) occur when a star passes close to a massive black hole, so that the tidal forces of the black hole exceed the binding energy of a star and cause it to be ripped apart. Part of the matter will fall onto the…
We describe the full nonlinear development of the superradiant instability for a charged massless scalar field, coupled to general relativity and electromagnetism, in the vicinity of a Reissner-Nordstrom-AdS black hole. The presence of the…
A supermassive black hole (SMBH) at the core of an active galactic nucleus (AGN) provides room for the elusive ultra-light scalar particles (ULSP) to be produced through a phenomenon called \textit{superradiance}. This phenomenon produces a…
The superradiance instability of rotating black holes leads to the formation of an ultralight boson cloud with distinctive observational signatures, making black holes an effective probe of ultralight bosons. However, around black holes in…
A distinct visual signature occurs in black holes that are surrounded by optically thin and geometrically thick emission regions. This signature is a sharp-edged dip in brightness that is coincident with the black-hole shadow, which is the…
Black hole superradiance is a powerful probe of ultralight axions. If nature contains a boson with a mass of order $10^{-12}\,$eV, $\textit{mere vacuum fluctuations}$ will lead to its efficient production around spinning stellar mass black…