Related papers: Hot, Retrograde Tilted MADs: Misaligned, Precessin…
Accreting X-Ray Binaries display a wide range of behaviours. Some of them are observed to spin up steadily, others to alternate between spin-up and spin-down states, sometimes superimposed on a longer trend of either spin up or spin down.…
We present a set of three-dimensional, global, general relativistic radiation magnetohydrodynamic simulations of thin, radiation-pressure-dominated accretion disks surrounding a non-rotating, stellar-mass black hole. The simulations are…
The assumption that black hole accretion disks possess an untorqued inner boundary, the so-called zero torque boundary condition, has been employed by models of black hole disks for many years. However, recent theoretical and observational…
Understanding the dynamics of low angular momentum accretion flow around black holes (BHs) is essential for probing extreme plasma behavior in strong gravity, where shock formation can naturally produce variability signatures. In this…
Binary black holes on quasicircular orbits with spins aligned with their orbital angular momentum have been testbeds for analytic and numerical relativity for decades, not least because symmetry ensures that such configurations are…
We demonstrate the importance of general relativistic apsidal precession in warped black hole accretion discs by comparing three - dimensional smoothed particle hydrodynamic simulations in which this effect is first neglected, and then…
The conventional accretion disk lore is that magnetized turbulence is the principal angular momentum transport process that drives accretion. However, when dynamically important large-scale magnetic fields thread an accretion disk, they can…
We present the results of three-dimensional global resistive magnetohydrodynamic (MHD) simulations of black hole accretion flows. General relativistic effects are simulated by using the pseudo-Newtonian potential. Initial state is an…
We present a discussion of two-dimensional magneto-hydrodynamics (MHD) configurations, concerning the equilibria of accretion disks of a strongly magnetized astrophysical object. We set up a viscoresistive scenario which generalizes…
We model gas inflow patterns onto circumstellar disks and the evolution of the pseudodisk using three-dimensional resistive MHD simulations. Starting from a prestellar core without turbulence and with a misalignment between the initial…
We investigate the accretion induced spin up of the black hole via numerical simulations. Our method is based on general-relativistic magneto-hydrodynamics of the slowly-rotating flows in the Kerr metric, where possibly transonic shock…
Accretion disks around supermassive black holes (SMBHs) in active galactic nuclei contain stars, stellar mass black holes, and other stellar remnants, which perturb the disk gas gravitationally. The resulting density perturbations in turn…
The radiation-driven warping instability discovered by Pringle holds considerable promise as the mechanism responsible for producing warped, precessing accretion disks in X-ray binaries. This instability is an inherently global mode of the…
While supermassive binary black holes inspiral toward merger they may also experience significant accretion of matter from a surrounding disk. We study the dynamics of this system, simultaneously describing the evolving spacetime and…
We study Lense-Thirring precession of inviscid and viscous misaligned $\alpha-$discs around a black hole using a gravitomagnetic term in the momentum equation. For weak misalignments, $i \lesssim 10^{\circ}$, the discs behave like rigid…
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 formation of protostellar disks out of molecular cloud cores is still not fully understood. Under ideal MHD conditions, the removal of angular momentum from the disk progenitor by the typically embedded magnetic field may prevent the…
A test particle orbit around an eccentric binary has two stationary states in which there is no nodal precession: coplanar and polar. Nodal precession of a misaligned test particle orbit centres on one of these stationary states. A low mass…
The Event Horizon Telescope Collaboration (EHTC) observed the Galactic centre source Sagittarius A* (Sgr A*) and used emission models primarily based on single ion temperature (1T) general relativistic magnetohydrodynamic (GRMHD)…
We present an exact analytical investigation of spin precession for a test gyroscope in the magnetized Kerr spacetime--an exact electrovacuum solution to the Einstein-Maxwell equations. Our approach accommodates arbitrary magnetic field…