Related papers: The Innermost Stable Circular Orbit in Compact Bin…
Modern astrophysical methods of determination of spins of rotating stellar-mass black hole in close binaries and of supermassive black holes in active galactic nuclei are briefly discussed. Effective spins of coalescing binary black holes…
We study spherically symmetric magnetically charged generic black hole solutions of general relativity coupled to non-linear electrodynamics (NED). For characteristic values of the generic spacetime parameters we give the position of…
As is well-known, asymptotically flat, static and spherically symmetric black holes do not admit stable bound orbits of massive/massless particles outside the horizon in higher-dimensional Einstein gravity. However, for massive particles,…
Binary black holes in which both spins are aligned with the binary's orbital angular momentum do not precess. However, the up-down configuration, in which the spin of the heavier (lighter) black hole is aligned (anti-aligned) with the…
The frequencies of the highest-frequency kilohertz QPOs recently discovered in some sixteen neutron stars in low-mass X-ray binary systems are most likely orbital frequencies. If so, these QPOs provide tight upper bounds on the masses and…
In this paper we have examined numerically exact configurations of close binary systems composed of incompressible fluids with internal flows. Component stars of binary systems are assumed to be circularly orbiting each other but rotating…
We study circular orbits that are tilted with respect to the equatorial plane around a Kerr black hole. We write the equations for the parameters of a tilted circular orbit in terms of the orbit's radius and the Carter constant, or…
We examine the dynamics of a neutral particle around a Kerr-Newman black hole, and in particular focus on the effects of the charge of the spinning black hole on the motion of the particle. We first consider the innermost stable circular…
Spin precession occurs in binary black holes whose spins are misaligned with the orbital angular momentum. Otherwise, the spin configuration is constant and the subsequent binary dynamics and gravitational-wave emission are much simpler. We…
We construct new models of black hole-neutron star binaries in quasiequilibrium circular orbits by solving Einstein's constraint equations in the conformal thin-sandwich decomposition together with the relativistic equations of…
In the present paper we investigate self-consistently slowly rotating neutron and strange stars in R-squared gravity. For this purpose we first derive the equations describing the structure of the slowly rotating compact stars in…
We investigate the dynamics of a neutral and a charged particle around a black hole in modified gravity immersed in magnetic field. Our focus is on the scalar-tensor-vector theory as modified gravity. We are interested to explore the…
We investigate the stable circular orbits of the spinning test particles around the accelerating Kerr black hole on the equatorial plane. To this end, we first calculate the equations of motion and analyze the parameter space for the…
We consider a situation where a light source orbiting the innermost stable circular orbit (ISCO) of the Kerr black hole is gently falling from the marginally stable orbit due to an infinitesimal perturbation. Assuming that the light source…
Neutron stars in binary orbit emit gravitational waves and spiral slowly together. During this inspiral, they are expected to have very little vorticity. It is in fact a good approximation to treat the system as having zero vorticity, i.e.,…
The study of off-equatorial orbits in razor-thin disks is still in its beginnings. Contrary to what was presented in the literature in recent publications, the vertical stability criterion for equatorial circular orbits cannot be based on…
Three-body interactions are expected to be common in globular clusters and in galactic cores hosting supermassive black holes. Here we consider an equal-mass binary-black-hole system in the presence of a third black hole. Using numerically…
We perform force-free simulations for a neutron star orbiting a black hole, aiming at clarifying the main magnetosphere properties of such binaries towards their innermost stable circular orbits. Several configurations are explored, varying…
Astrophysical black holes are invariably embedded in matter environments whose gravitational influence can alter key strong-field features of the spacetime. In this work, we investigate the impact of spherically symmetric dark-matter…
In this paper, we investigate the optical properties of a black hole in non-minimal Einstein-Yang-Mills theory, illuminated by a thin accretion disk. In our setup, matter follows stable circular orbits outside the innermost stable circular…