Related papers: Spherical accretion by normal and phantom Einstein…
We study the spherically symmetric collapse of a real, minimally coupled, massive scalar field in an asymptotically Einstein-de Sitter spacetime background. By means of an eikonal approximation for the field and metric functions, we obtain…
The recent birth of gravitational wave astronomy invites a new generation of precision tests of general relativity. Signatures of black hole (BH) mergers must be systematically explored in a wide spectrum of modified gravity theories. Here,…
We examine the accretion process onto the black hole with a string cloud background, where the horizon of the black hole has an enlarged radius $r_H=2 M/(1-\alpha)$, due to the string cloud parameter $\alpha\; (0 \leq \alpha < 1)$. The…
We study critical phenomena in the gravitational collapse of a radiation fluid. We perform numerical simulations in both spherical symmetry and axisymmetry, and observe critical scaling in both supercritical evolutions, which lead to the…
In this paper, we consider the problems of spherical gravitational collapse and accretion using a spherically symmetric, spatially homothetic spacetime, that is, as an exact solution (cqg1) of the field equations of general relativity.…
We numerically integrate the semiclassical equations of motion for spherically symmetric Einstein-Maxwell theory with a dilaton coupled scalar field and look for zero temperature configurations. The solution we find is studied in detail…
The pulsation equations for spherically symmetric black hole and soliton solutions are brought into a standard form. The formulae apply to a large class of field theoretical matter models and can easily be worked out for specific examples.…
We present new accretion solutions of a polytropic perfect fluid onto an f(R)-gravity de Sitter-like black hole. We consider two f(R)-gravity models and obtain finite-period cyclic flows oscillating between the event and cosmological…
We construct static multicenter solutions of phantom Einstein-Maxwell-dilaton theory from null geodesics of the target space, leading to regular black holes without spatial symmetry for certain discrete values of the dilaton coupling…
A slowly rotating black hole solution in Einstein-Maxwell-dilaton gravity was considered. Having used the obtained solution we investigated thermodynamic functions such as black hole's temperature, entropy and heat capacity. In addition to…
Recently it was demonstrated that by adding to the Einstein-Hilbert action a series in powers of the curvature invariants with specially chosen coefficients one can obtain a theory of gravity which has spherically symmetric solutions…
We shortly summarize the standard current knowledge on the structure of the accretion flow onto black holes in galactic binary systems and in active galactic nuclei. We stress the similarities and differences between the two types of…
The characteristics and images of Einstein-Maxwell-Dilaton (EMD) black holes are examined in this paper, focusing on their effective potential, photon trajectories, and images with thin and thick accretion disks. We found that the shadow…
In this work we study steady and spherical relativistic dust accretion onto a static and spherically symmetric scale--dependent black hole. In particular we consider a polytropic scale--dependent black hole as a central object and obtain…
We discuss the new class of static axially symmetric black hole solutions obtained recently in Einstein-Yang-Mills and Einstein-Yang-Mills-dilaton theory. These black hole solutions are asymptotically flat and they possess a regular event…
The hydrodynamic behaviour of perfect fluid orbiting around black holes in spherically symmetric spacetime for various alternative gravity theories has been investigated. For this purpose we have assumed an uniform distribution for the…
We study the evaporation process of a 2D black hole in thermal equilibrium when the ingoing radiation is switched off suddenly. We also introduce global symmetries of generic 2D dilaton gravity models which generalize the extra symmetry of…
With the goal of providing more accurate and realistic estimates of the secular behavior of the mass accretion and drag rates in the "common-envelope" scenario encountered when a black hole or a neutron star moves in the stellar envelope of…
Spectral formation in steady state, spherical accretion onto neutron stars and black holes is examined by solving numerically and analytically the equation of radiative transfer. The photons escape diffusively and their energy gains come…
We study the quasi-normal modes of the charged scalar perturbations in the background of the Einstein-Maxwell-aether black hole through three methods (WKB method, continued fraction method, generalized eigenvalue method). Then we propose…