Related papers: Cusps without chaos
We study the linear perturbations of collisionless near-Keplerian discs. Such systems are models for debris discs around stars and the stellar discs surrounding supermassive black holes at the centres of galaxies. Using a finite-element…
We consider a wide class of static spherically symmetric black holes of arbitrary dimension with a photon sphere (a hypersurface on which a massless particle can orbit the black hole on unstable circular null geodesics). This class includes…
If supermassive black holes in centres of galaxies form by merging of black-hole remnants of massive Population III stars, then there should be a few black holes of mass one or two orders of magnitude smaller than that of the central ones,…
We present dynamical models for the massive globular cluster G1. The goal is to measure or place a significant upper limit on the mass of any central black hole. Whether or not globular clusters contain central massive black holes has…
We have examined the effect of slow growth of a central black hole on spherical galaxies that obey S\'ersic or $R^{1/m}$ surface-brightness profiles. During such growth the actions of each stellar orbit are conserved, which allows us to…
Using semi-analytical models of galaxy formation, the origin of boxy and disky elliptical galaxies is investigated. We find that the simple scenario, motivated by N-body simulations, in which the isophotal shape is only dependent on the…
A surprisingly large number of galaxies with masses of $\sim10^9-10^{10}M_\odot$ at redshifts of $z\geq9$ are discovered with the James Webb Space Telescope. A possible explanation for the increase in the mass function can be the presence…
Establishing the relative role of internally and externally driven mechanisms responsible for disc and bulge growth is essential to understand the evolution of disc galaxies. In this context, we have studied the physical properties of disc…
We report on a new class of solutions of black hole accretion disks that we have found through three-dimensional, global, radiative magnetohydrodynamic simulations in general relativity. It combines features of the canonical thin, slim and…
N-body simulations and analytical calculations of the gravitational collapse in an expanding universe predict that halos should form with a diverging inner density profile, the cusp. There are some observational indications that the dark…
We describe stationary and axisymmetric gas configurations surrounding black holes. They consist of a collisionless relativistic kinetic gas of identical massive particles following bound orbits in a Schwarzschild exterior spacetime and are…
Compact remnants -- stellar mass black holes and neutron stars formed in the inner few parsec of galactic centres are predicted to sink into the central parsec due to dynamical friction on low mass stars, forming a high concentration cusp…
We investigate non-linear, spherically symmetric solutions to the coupled system of a quintessence field and Einstein gravity. In the presence of a scalar potential, we find regular solutions that to an outside observer very closely…
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…
(Abridged:) Schwarzschild's method was used to construct equilibrium solutions to the collisionless Boltzmann equation corresponding to a Plummer sphere, which were compared with analytical results to test the robustness of the numerical…
Observations reveal that mature spiral galaxies consist of stars, gases and plasma approximately distributed in a thin disk of circular shape, usually with a central bulge. The rotation velocities quickly increase from the galactic center…
Given the dimensions (including thickness) of a galaxy, and its rotation profile, a method is shown that finds the mass and density distributions in the defined envelope that will cause that rotation profile with near-exact speed matches.…
In several previous investigations we presented models of triaxial stellar systems, both cuspy and non cuspy, that were highly stable and harboured large fractions of chaotic orbits. All our models had been obtained through cold collapses…
We discuss the kinematical structure of a two-parameter family of isotropic models with a central black hole. The family contains the slope of the central density cusp and the relative black hole mass as parameters. Most of the basic…
An origin is sought for the ubiquity of cusps, both in computer simulations of halo formation in hierarchical clustering cosmogonies and in observations of galactic nuclei by the Hubble Space Telescope (HST). The encounters of merging…