Related papers: RDM-stars and related topics
The scaling of disk galaxy rotation velocity with baryonic mass (the "Baryonic Tully-Fisher" relation, BTF) has long confounded galaxy formation models. It is steeper than the M ~ V^3 scaling relating halo virial masses and circular…
In this work we use the recently introduced concept of self-interacting dark matter with scale-dependent equation of state, and we provide an analytic model of dark matter that can produce viable rotation curves even for…
We construct two models of the formation a galaxy with a central black hole, starting from a small initial fluctuation at recombination. This is an application of previously developed methods to find a Lemaitre-Tolman model that evolves…
A sample of 22 spiral galaxies compiled from published data is studied. The galaxy rotation curves pass through a maximum distance of more than $\sim 1$ kpc from the center with a subsequent decrease in the rotation velocity. The galaxy…
We shall study the formation of a particular class of regular black holes from the gravitational collapse of a massive star. The inside geometry is described by spatially flat Friedmann-Robertson-Walker metric and the stellar matter is…
We have studied the origin of the Tully-Fisher relation by analysing hydrodynamical simulations in a Lambda-CDM universe. We found that smaller galaxies exhibit lower stellar masses than those predicted by the linear fit to high mass…
A new class of analytic charged spherically symmetric black hole solutions, which behave asymptotically as flat or (A)dS spacetimes, is derived for specific classes of $f(R)$ gravity, i.e., $f(R)=R-2\alpha\sqrt{R}$ and…
Resonant relaxation (RR) of orbital angular momenta occurs near massive black holes (MBHs) where the stellar orbits are nearly Keplerian and so do not precess significantly. The resulting coherent torques efficiently change the magnitude of…
We examine the disc--jet connection in stellar mass and supermassive black holes by investigating the properties of their compact emission in the X-ray and radio bands. We compile a sample of ~100 active galactic nuclei with measured mass,…
Recently, some fast radio burst (FRB) repeaters were reported to exhibit complex, diverse variations of Faraday rotation measures (RMs), which implies that they are surrounded by an inhomogeneous, dynamically evolving, magnetized…
Tidal disruptions of stars on the equatorial plane orbiting Kerr black holes have been widely studied. However thus far, there have been fewer studies of stars in inclined precessing orbits around a Kerr black hole. In this paper, we use…
The collapsar model of long gamma-ray bursts (GRBs) indicates that they may trace the star formation history. So long GRBs may be a useful tool of measuring the high-redshift star formation rate (SFR). The collapsar model explains GRB…
We present simulations of thin accretion disks around black holes investigating a mean-field disk dynamo in our resistive GRMHD code (Vourellis et al. 2019) that is able to produce a large scale magnetic flux. We consider a weak seed field…
Mergers of neutron stars with black holes have been suggested as candidates for short gamma-ray bursts. They have also been studied for their potential as gravitational wave sources observable with ground-based detectors. For these…
Short Gamma-Ray Bursts (GRBs) are explosions of cosmic origin believed to be associated with the merger of two compact objects, either two neutron stars, or a neutron star and a black hole. The presence of at least one neutron star has long…
Fuzzy dark matter (FDM) is a proposed modification for the standard cold dark matter (CDM) model motivated by small-scale discrepancies in low-mass galaxies. Composed of ultra-light (mass $\sim 10^{-22}$ eV) axions with kpc-scale de Broglie…
Using the latest sample of 48 spiral galaxies having a directly measured supermassive black hole mass, $M_{BH}$, we determine how the maximum disk rotational velocity, $v_{max}$ (and the implied dark matter halo mass, $M_{DM}$), correlates…
We recover spiral and barred spiral patterns in disk galaxy simulations with a Wave Dark Matter (WDM) background (also known as Scalar Field Dark Matter (SFDM), Ultra-Light Axion (ULA) dark matter, and Bose-Einstein Condensate (BEC) dark…
The supermassive black holes at the centers of galaxies may be surrounded by dark matter spike, which could leave detectable imprints on the gravitational wave signals they emit. In this work, combining the mass model of M87, we present…
We consider the spherically symmetric black hole solution of the Randall-Sundrum (RS) model. This asymptotically-Schwarzschild solution was found by Abdolrahimi, Cation, Page and Yaghoobpour-Tari (ACPY-solution). We investigate the specific…