Related papers: Spin-Induced Disk Precession in Sagittarius A*
We discuss the timescales for alignment of black hole and accretion disc spins in the context of binary systems. We show that for black holes that are formed with substantial angular momentum, the alignment timescales are likely to be at…
We determine the spin of a supermassive black hole in the context of discseismology by comparing newly detected quasi-periodic oscillations (QPOs) of radio emission in the Galactic centre, Sagittarius A* (Sgr A*), as well as infrared and…
The low accretion rate inferred for the GC source Sgr A* requires a distinct type of accretion disk -- a starving disk. We investigate the structure of this type of disk within the framework of thin Keplerian disk models taking into account…
Sagittarius A* (Srg A*), the supermassive black hole at the center of the Milky Way, provides a unique laboratory to study accretion dynamics and plasma processes near the event horizon. We investigated the variability and polarization…
Black holes in X-ray binaries are often assumed to be rotating perpendicular to the plane of the accretion disk and parallel to the orbital plane of the binary. While the Bardeen-Petterson effect forces the inner part of the accretion disk…
We present numerical simulations of stellar wind dynamics in the central parsec of the Galactic centre, studying in particular the accretion of gas on to Sgr A*, the super-massive black hole. Unlike our previous work, here we use…
(abridged) The black hole Sagittarius A* (Sgr A*) is a prime target for next-generation Earth-space very-long-baseline interferometry missions such as the Black Hole Explorer (BHEX), which aims to probe baselines of the order of 20…
The Galactic Center is the closest galactic nucleus that can be studied with unprecedented angular resolution and sensitivity. We summarize recent basic observational results on Sagittarius A* and the conditions for star formation in the…
The mm to sub-mm spectrum of Sgr A* at the Galactic center, as well as its polarization characteristics, are consistent with the inner 10 Schwarzschild radii of a tight Keplerian emitting region of hot, magnetized, orbiting gas. This plasma…
Millimeter very-long baseline interferometry (mm-VLBI) provides the novel capacity to probe the emission region of a handful of supermassive black holes on sub-horizon scales. For Sagittarius A* (Sgr A*), the supermassive black hole at the…
An accretion disk formed around a supermassive black hole (SMBH) after it disrupts a star is expected to be initially misaligned with respect to the black hole's equatorial plane. This misalignment induces relativistic torques (the…
The Event Horizon Telescope (EHT) Collaboration produced the first image of the apparent shadow of the central black hole of Sagittarius\,A$^*$ (\sgra). \sgra source structure varies significantly on timescales shorter than the duration of…
Luminous active galactic nuclei (AGN) and X-Ray binaries (XRBs) often contain geometrically thin, radiatively cooled accretion discs. According to theory, these are -- in many cases -- initially highly misaligned with the black hole…
Sagittarius A* exhibits frequent flaring activity across the electromagnetic spectrum. Signatures of an orbiting hot spot have been identified in the polarized millimeter wavelength light curves observed with ALMA in 2017 immediately after…
The predicted radio flux for nearby ellipticals by the canonical ADAF(advection-dominated accretion flow) model is well above the observations. If the mass accretion rate favored by the numerical simulation were adopted, the ADAF model…
The compact radio source Sagittarius A (Sgr A) at the centre of our Galaxy harbours a supermassive black hole, whose mass has been measured from stellar orbital motions. Sgr A is therefore the nearest laboratory where super-massive black…
We study accretion rates during the gravitational wave-driven merger of a binary supermassive black hole embedded in an accretion disc, formed by gas driven to the centre of the galaxy. We use 3D simulations performed with PHANTOM, a…
In the first paper of this series, using analytic tools, we examined how the evolution and structure of a massive accretion disk may be influenced by the deposition of mass and angular momentum by an infalling Bondi-Hoyle wind. Such a mass…
In active galactic nuclei, X-ray illumination of the accretion disk around a supermassive black hole (SMBH) results in the production of the K$\alpha$ fluorescent line of iron, which provides insights into accretion physics and SMBH spins.…
We study model images and polarization maps of Sagittarius A* at 230 GHz. We post-process GRMHD simulations and perform a fully relativistic radiative transfer calculation of the emitted synchrotron radiation to obtain polarized images for…