The innermost part of the Nuclear Star Cluster is known as the S cluster that consists mostly of young B-type stars. The origin of these young stars at the scale of 1000 gravitational radii from Sgr A has remained a puzzle. The brightest of those stars have been crucial for determining the mass of Sgr A as well as for testing gravitational theories in the strong-field limit. Recently, Ali et...
Sagittarius A* is a super massive black hole in the center of our galaxy observed across the electromagnetic spectrum for decades. Moreover, it is the primary target of the Event Horizon Telescope (EHT) and the GRAVITY collaboration, which observe in the 230 GHz (EHT) and the NIR (GRAVITY). The compact radio emission is expected to be thermal radiation from the vicinity of the black hole. The...
We examine limits to the energy to which cosmic rays can be accelerated by the
termination shocks in the southern jet of radiogalaxy 3C 445. At high radio frequencies, the southern hotspot shows two sub structures named SE and SW.
By using the observed flux density at 22 GHz in SE and SW, we find that a
hotspot magnetic field of about 500 micro Gauss is required to explain the...
Astrophysical black holes in nuclei of galaxies are of indisputable relevance to the current research. These extreme objects are of immense interest to pure relativists as well as observational astronomers. We will present an overview of selected aspects of physical processes occurring in the inner regions of Active Galactic Nuclei (AGN). Observational evidence strongly suggests that strong...
The central super-massive black hole of the Milky Way, Sgr A, accretes at a very low rate making it a very underluminous galactic nucleus. Despite the tens of Wolf-Rayet stars present within the inner parsec supplying $\sim10^{−3}\rm M_{\odot}\ yr^{-1}$ in stellar winds, only a negligible fraction of this material ($<10^{-4}$) ends up being accreted onto Sgr A. The recent discovery of cold...