Related papers: Black Holes as Dark Matter
Stellar-mass black holes ($3$ $M_\odot \lesssim M_{\rm BH} \lesssim 150$ $M_\odot$) are the natural product of the evolution of heavy stars ($M_{\rm star} \gtrsim 20$ $M_\odot$). In our Galaxy, we expect $10^8$-$10^9$ stellar-mass black…
The spectrum of positrons and antiprotons produced by the outflow of high temperature matter surrounding microscopic black holes is calculated for energies between five GeV and the Planck energy. The results may be applicable for the last…
A discussion at a Scientific American level of the idea that the constituents of the dark mater in galactic halos are primordial intermediate-mass black holes with masses between ten and one hundred thousand times the solar mass.
We study properties of particles with zero or negative energy and a nonzero orbital angular momentum in the ergosphere of a rotating black hole. We show that the sign of the particle energy is uniquely determined by the angular velocity of…
A comparison is made of a range of proposals to include free and bound black holes as either a small component or the dominant constituent of dark matter. The hypothesis that dark matter consists of atomic gravitationally bound primordial…
The entropy of a black hole can be obtained by counting states in loop quantum gravity. The dominant term depends on the Immirzi parameter involved in the quantization and is proportional to the area of the horizon, while there is a…
The existence of exact solutions which represent a lattice of black holes at a scalar-field-dominated cosmological bounce suggests that black holes could persist through successive eras of a cyclic cosmology. Here we explore some remarkable…
It is discussed how the ideas of entropy and the second law of thermodynamics, conceived long ago during the nineteenth century, underly why cosmological dark matter exists and originated in the first three years of the universe in the form…
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…
It is now widely accepted that most of mass--energy in the universe is unobserved except by its gravitational effects. Baryons make only about 4% of the total, with "dark matter" making up about 23% and the "dark energy" responsible for the…
By studying the present cosmological data, particularly on CMB, SNeIA and LSS, we find that the future fate of the universe, for simple linear models of the dark energy equation-of-state, can vary between the extremes of (I) a divergence of…
A highly accurate computer program is used to study axially symmetric and stationary spacetimes containing a Black Hole surrounded by a ring of matter. It is shown that the matter ring affects the properties of the Black Hole drastically.…
We investigate the physics of black holes in the light of the quantum theoretical framework proposed in [1]. It is argued that black holes are completely non-local objects, and that the only one which really exists is the universe itself.
We show that dark matter with certain minimal properties can convert the majority of baryons in galaxies to black holes over hundred trillion year timescales. We argue that this has implications for cosmologies which propose that new…
Primordial black holes (PBHs) with mass $10^{16}-10^{17}$ g almost escape constraints from observations so could essentially contribute to dark matter density. Hawking evaporation of such PBHs produces with a steady rate $\gamma$- and…
We argue that the statistical entropy relevant for the thermal interactions of a black hole with its surroundings is (the logarithm of) the number of quantum microstates of the hole which are distinguishable from the hole's exterior, and…
The new, rapidly developing field of theoretical research --- studies of dark energy interacting with black holes (and, in particular, accreting onto black holes) --- is reviewed. The term `dark energy' is meant to cover a wide range of…
Black holes contain more entropy than any other component of the observable universe. Gravitational-wave observations from LIGO and Virgo have shown evidence of a previously unknown black hole mass range, which provides new information to…
Black holes are thermodynamic objects, but despite recent progress, the ultimate statistical mechanical origin of black hole temperature and entropy remains mysterious. Here I summarize an approach in which the entropy is viewed as arising…
The different methods of determination of black holes (BHs) masses are presented for three classes of BHs observed in the Universe: stellar mass BHs, intermediate mass BHs (IMBHs) and supermassive BHs (SBHs). The results of these…