Related papers: Highly-collimated, magnetically-dominated jets aro…
We investigate numerical convergence in simulations of magnetically arrested disks around spinning black holes. Using the general-relativistic magnetohydrodynamics code Athena++, we study the same system at four resolutions (up to an…
Black hole (BH) accretion flows and jets are dynamic hot relativistic magnetized plasma flows whose radiative opacity can significantly affect flow structure and behavior. We describe a numerical scheme, tests, and an astrophysically…
Black hole (BH) accretion disks are often coupled to ultramagnetized and tenuous plasma coronae close to their central BHs. The coronal magnetic field can exchange energy between the disk and the BH, power X-ray emission, and lead to jetted…
We investigate a relativistic fluid jet driven by radiation from a shocked accretion disc around a non-rotating black hole approximated by Paczy\'nski-Wiita potential. The sub-Keplerian and Keplerian accretion rates control the shock…
The dynamics of a black hole traveling through a plasma--a general relativistic extension of the classic Bondi-Hoyle-Lyttleton (BHL) accretion problem--can be related to a variety of astrophysical contexts, including the aftermath of binary…
We discuss the problem of the formation of a large-scale magnetic field in the accretion disks around black holes, taking into account the non-uniform vertical structure of the disk. The high electrical conductivity of the outer layers of…
For almost four decades, since the discovery of quasars, mounting observational evidence has accumulated that black holes indeed exist in nature. In this paper, I present a theoretical and numerical (Monte Carlo) fully relativistic 4-D…
It is widely believed that relativistic jets in X-ray binaries and active-galactic nuclei are powered by the rotational energy of black holes. This idea is supported by general-relativistic magnetohydrodynamic (GRMHD) simulations of…
A simple look at the steady high-energy Universe reveals a clear correlation with outflows generated around compact objects (winds and jets). In the case of relativistic jets, they are thought to be produced as a consequence of the…
MHD jet equilibria that depend on source properties are obtained using a simplified model for stationary, axisymmetric and rotating magnetized outflows. The present rotation laws are more complex than previously considered and include a…
These lectures provide a detailed introduction to the electro- dynamics of black holes. A simplified derivation of the basic membrane equations for stationary, axisymmetric black holes is given. The general theory is applied to idealized…
We perform the first numerical simulations modeling the inflow and outflow of magnetized plasma in the Kerr-Sen spacetime, which describes classical spinning black holes (BHs) in string theory. We find that the Blandford-Znajek (BZ)…
Recent work has called into question whether nature can extract the rotational energy of a black hole via electromagnetic fields by appealing to an alleged ability to absorb current. We describe the strategies needed to properly treat the…
The stability of astrophysical jets in the linear regime is investigated by presenting the methodology to find the growth rates of the various instabilities. We perturb a cylindrical axisymmetric steady jet, linearize the relativistic ideal…
We explore the possibility of formation of steady internal shocks in jets around black holes. We consider a fluid described by a relativistic equation of state, flowing about the axis of symmetry ($\theta=0$) in a Schwarzschild metric. We…
Spinning supermassive black holes (BHs) in active galactic nuclei (AGN) magnetically launch relativistic collimated outflows, or jets. Without angular momentum supply, such jets are thought to perish within $3$ orders of magnitude in…
Numerical simulations combined with simple analytical arguments are used to reach a number of important conclusions on the nature of the Blandford-Znajek mechanism. We show that, just like in the Penrose mechanism and in the MHD models of…
Employing 3D GRMHD simulation, we study the images of a geometrically thin jet, whose emissions concentrate on its surface, for accretion system surrounding a central spinning BH. By introducing a strong magnetic field, we observe three…
Despite all the already existing observational data, current models still cannot explain completely the excessive energy output and the time variability of GRB. One of the reasons for this is the lack of a good model of the central engine…
We study force-free magnetospheres in the Blandford-Znajek process from rapidly rotating black holes by adopting the near-horizon geometry of near-extreme Kerr black holes (near-NHEK). It is shown that the Znajek regularity condition on the…