Related papers: Living in a Low Density Black Hole, Non-Expanding …
If spacetime torsion couples to the intrinsic spin of matter according to the Einstein-Cartan-Sciama-Kibble theory of gravity, then the resulting gravitational repulsion at supranuclear densities prevents the formation of singularities in…
We analyze a sample of 32 galaxies for which a dynamical estimate of the mass of the hot stellar component, M_bulge, is available. For each of these galaxies, we calculate the mass of the central black hole, M_BH, using the tight empirical…
Supermassive black holes are thought to be relics of quasars, and their numbers and masses are therefore related to the quasar luminosity function and its evolution with redshift. We have used the relationship between black hole mass and…
Black holes are a common feature of the Universe. They are observed as stellar mass black holes spread throughout galaxies and as supermassive objects in their centres. Observations of stars orbiting close to the centre of our Galaxy…
Based on constraints from microlensing and disk stability, both with and without limitations from wide binary surveys, we estimate the total number and entropy of intermediate mass black holes. Given the visible universe comprises $10^{11}$…
Astronomers have discovered two populations of black holes: (i) stellar-mass black holes with masses in the range 5 to 30 solar masses, millions of which are present in each galaxy in the universe, and (ii) supermassive black holes with…
The inspiral and merger of two black holes produces a remnant black hole with mass and spin determined by the properties of its parent black holes. Using the inferred population properties of component black holes from the first two and a…
If the stellar population of the bulge contains black holes formed in the final core collapse of ordinary stars with M \ga 30 M_{\odot}, then about 25,000 stellar mass black holes should have migrated by dynamical friction into the central…
A black hole is the end state of the gravitational collapse of massive stars. However, a typical black hole contains a singularity and to avoid singularity formation we have to violate a strong energy condition that states that gravity must…
The stellar mass in disk galaxies scales approximately with the fourth power of the rotation velocity, and the masses of the central black holes in galactic nuclei scale approximately with the fourth power of the bulge velocity dispersion.…
Recent surveys suggest that most or all normal galaxies host a massive black hole with 1/100 to 1/1000 of the visible mass of the spheroid of the galaxy. Various lines of argument suggest that these galaxies have merged at least once in our…
We establish constraints on the mass and abundance of black holes in the Galactic halo by determining their impact on globular clusters which are conventionally considered to be little evolved. Using detailed Monte Carlo simulations and…
In this paper we report results of collisional N-body simulations of the dynamical evolution of equal-mass star clusters containing a massive central black hole. Each cluster is composed of between 5,000 to 180,000 stars together with a…
In 1997, an extension of general relativity was proposed that predicts the dark energy density \Lambda\ to vary linearly with the total number of macroscopic black holes in the universe. We explore this prediction and find that \Lambda\…
Supermassive black holes are believed to be ubiquitous at the centers of galaxies. Measuring their masses is extremely challenging yet essential for understanding their role in the formation and evolution of cosmic structure. We present a…
Massive black holes have been discovered in all closely examined galaxies with high velocity dispersion. The case is not as clear for lower-dispersion systems such as low-mass galaxies and globular clusters. Here we suggest that above a…
Microscopic black holes explode with their temperature varying inversely as their mass. Such explosions would lead to the highest temperatures in the present universe, all the way to the Planck energy. The possibility that a…
Globular star clusters contain thousands to millions of old stars packed within a region only tens of light years across. Their high stellar densities make it very probable that their member stars will interact or collide. There has been…
Our universe has multiple examples of unexplained gravitational losses in black holes and neutron stars. The smallest black holes of about 4 solar masses means the maximum baryon density \rho \approx 10^{17} grams/cm^3. Any collapse of the…
Black hole is called optimal if information content is minimal at the University region, consisting of usual substance and one(n) black hole(s). Optimal black hole mass does not depend on the mass of the Universe region. Optimal black holes…