In general relativity, isolated black holes are invisible due to the infinitely large redshift of
photons propagating from the event horizon to a remote observer. However, the dark …

Black holes are unique among astrophysical sources: they are the simplest macroscopic
objects in the Universe, and they are extraordinary in terms of their ability to convert energy …

We analytically compute the observational appearance of an isotropically emitting point
source on a circular, equatorial orbit near the horizon of a rapidly spinning black hole. The …

General relativity predicts that the Kerr black hole develops qualitatively new and surprising
features in the limit of maximal spin. Most strikingly, the region of spacetime near the event …

Rebirth of X-ray polarimetric instruments will have a significant impact on our knowledge of
compact accreting sources. The properties of inner-accreting regions of active galactic …

We derive the precise late-time asymptotics for solutions to the wave equation on extremal
Reissner–Nordström black holes and explicitly express the leading-order coefficients in …

In this study, we develop a simplified magnetofluid model in the framework of GRMHD. We
consider an ideal, adiabatic fluid composed of two components, ions and electrons, having a …

Accretion discs around stellarmass black holes (BHs) emit radiation peaking in the soft X-
rays when the source is in the thermal state. The emerging photons are polarized and, for …

We investigate the motions of charged particles in the near horizon region of an extreme
Kerr black hole with weak electromagnetic fields. There is an enhanced symmetry in the …

The study of radiation emitted from black hole (BH) accretion discs represents a crucial way
to understand the main physical properties of these sources, and in particular the BH spin …