相关论文: Structure and Instability of the Ionization Fronts…
We examine the role of ionizing radiation emitted from black holes (BHs) in suppressing the growth of the Rayleigh-Taylor instability (RTI) across the ionization front (I-front) that forms when the gas fueling the BH is neutral. We use…
Ionization front instabilities have long been of interest for their suspected role in a variety of phenomena in the galaxy, from the formation of bright rims and 'elephant trunks' in nebulae to triggered star formation in molecular clouds.…
An ionization front (IF) surrounding an H II region is a sharp interface where a cold neutral gas makes transition to a warm ionized phase by absorbing UV photons from central stars. We investigate the instability of a plane-parallel D-type…
Radiative cooling by metals in shocked gas mediates the formation of ionization front instabilities in the galaxy today that are responsible for a variety of phenomena in the interstellar medium, from the morphologies of nebulae to…
In this third paper of a series, we study the growth and luminosity of black holes (BHs) in motion with respect to their surrounding medium. We run a large set of two-dimensional (2D) axis-symmetric simulations to explore a large parameter…
Ionization fronts, the sharp radiation fronts behind which H/He ionizing photons from massive stars and galaxies propagate through space, were ubiquitous in the universe from its earliest times. The cosmic dark ages ended with the formation…
We present the first realistic 3D simulations of flame front instabilities during type I X-ray bursts. The unperturbed front is characterised by the balance between the pressure gradient and the Coriolis force of a spinning neutron star…
Coalescence of intermediate-mass black holes (IMBHs) as a result of the migration toward galactic centers via dynamical friction may contribute to the formation of supermassive BHs. Here we reinvestigate the gaseous dynamical friction,…
We present results from a numerical study of the runaway instability of thick discs around black holes. This instability is an important issue for most models of cosmic gamma-ray bursts, where the central engine responsible for the initial…
We investigate hydrodynamic instability of accelerating ionization fronts using two dimensional hydrodynamic simulations that include detailed energy deposition and release due to the absorption of UV radiation, recombination of hydrogen,…
Accretion of gas and interaction of matter and radiation are at the heart of many questions pertaining to black hole (BH) growth and coevolution of massive BHs and their host galaxies. To answer them it is critical to quantify how the…
We consider the scenario of a magnetic field orthogonal to a front separating two media of different temperatures and densities, such as cold and warm interstellar gas, in a 2-D plane-parallel geometry. A linear stability analysis is…
We discuss two important instability mechanisms that may lead to the limit-cycle oscillations of the luminosity of the accretion disks around compact objects: ionization instability and radiation-pressure instability. Ionization instability…
Numerical-relativity simulation is performed for rapidly spinning black holes (BHs) in a higher-dimensional spacetime of special symmetries for the dimensionality $6 \leq d \leq 8$. We find that higher-dimensional BHs, spinning rapidly…
We simulate the ionization environment of z ~ 20 luminous objects formed within the framework of the current CDM cosmology and compute their UV escape fraction. These objects are likely single very massive stars that are copious UV…
We carried out three-dimensional global resistive magnetohydrodynamic (MHD) simulations of the cooling instability in optically thin hot black hole accretion flows by assuming bremsstrahlung cooling. General relativistic effects are…
We study the stability of standing shock waves in advection-dominated accretion flows into a Schwarzschild black hole by 2D general relativistic hydrodynamic simulations as well as linear analysis in the equatorial plane. We demonstrate…
We put forward an attempt towards building a possible theoretical model to understand the observer dependent thermalization of black hole horizon. The near horizon Hamiltonian for a massless, chargeless particle is $xp$ type. This is…
Some of the accreting black holes exhibit much stronger variability patterns than the usual stochastic variations. Radiation pressure instability is one of the proposed mechanisms which could account for this effect. We aim to model…
We examine the effects of photon bubble instability in radiation-dominated accretion disks such as those found around black holes in active galactic nuclei and X-ray binary star systems. Two- and 3-D numerical radiation MHD calculations of…