Related papers: Black Holes Constitute All Dark Matter
From the observed results of the space distribution of quasars we deduced that neutrino mass is about10^(-1) eV. The fourth stable elementary particle (delta particle) with mass about 10^(0) eV can help explain the energy resource mechanism…
A black hole considered as a part of a thermodynamical system possesses the Bekenstein-Hawking entropy $S_H =A_H /(4l_{\mbox{\scriptsize{P}}}^2)$, where $A_H$ is the area of a black hole surface and $l_{\,\mbox{\scriptsize{P}}}$ is the…
In recent work we have extended the theory that dark matter is composed of primordial black hole (PBHs) to extremely high masses and made an assumption that the holographic entropy bound is saturated. Astrophysicists have recently suggested…
Observational evidence has been mounting for the existence of intermediate mass black holes (IMBHs, 10^2-10^5 Msun), but observing them at all, much less constraining their masses, is very challenging. In one theorized formation channel,…
Classically, the black hole (BH) horizon is a rigid surface of infinite redshift; whereas the uncertainty principle dictates that the semiclassical (would-be) horizon cannot be fixed in space nor can it exhibit any divergences. We propose…
The Kerr-Newman metric is the unique vacuum solution of the General Relativistic field equations, in which any singularities or spacetime pathologies are hidden behind horizons. They are believed to describe the spacetimes of massive…
Intermediate mass black holes (IMBHs) are an (as yet) elusive class of black holes that are expected to lie in the $10^2-10^5\,M_{\odot}$ range, between the firmly established stellar-mass black holes and ${\gtrsim}10^6\,M_{\odot}$…
While until recently they were often considered as exotic objects of dubious existence, in the last decades there have been overwhelming observational evidences for the presence of stellar mass black holes in binary systems, supermassive…
The distortion of the spacetime structure in the surroundings of black holes affects the trajectories of light rays. As a consequence, black holes can act as gravitational lenses. Observations of type Ia supernovas, show that our Universe…
We show that primordial (nearly) extremal black holes with a wide range of masses from the Planck scale to around $10^9$ g could be cosmologically stable and explain dark matter, given a dark electromagnetism and a heavy dark electron. For…
A galaxy halo may contain a large number of intermediate mass black holes (IMBHs) with masses in the range of 10^{2-6} solar mass. We propose to directly detect these IMBHs by observing multiply imaged QSO-galaxy or galaxy-galaxy strong…
The proposal of a galactic population of intermediate mass black holes (IMBHs), forming dark matter (DM) ``mini-spikes'' around them, has received considerable attention in recent years. In fact, leading in some scenarios to large…
We consider a class of black holes for which the area of the two-dimensional spatial cross-section has a minimum on the horizon with respect to a quasiglobal (Krusckal-like) coordinate. If the horizon is regular, one can generate a tubelike…
To what extent are all astrophysical, dark, compact objects both black holes (BHs) and described by the Kerr geometry? We embark on the exercise of defying the universality of this remarkable idea, often called the "Kerr hypothesis". After…
Dark matter is a fundamental constituent of the universe, which is needed to explain a wide variety of astrophysical and cosmological observations. Although the existence of dark matter was first postulated nearly a century ago and its…
It has been claimed in Ref.[arXiv:1712.02240] that massive primordial black holes (PBH) cannot constitute all of the dark matter (DM), because their gravitational-lensing imprint on the Hubble diagram of type Ia supernovae (SN) would be…
It has recently been suggested that black holes may be described as condensates of weakly interacting gravitons at a critical point, exhibiting strong quantum effects. In this paper, we study a model system of attractive bosons in one…
There is a debate as to what is the value of the the entropy $S$ of extremal black holes. There are approaches that yield zero entropy $S=0$, while there are others that yield the Bekenstein-Hawking entropy $S=A_+/4$, in Planck units. There…
The dark energy issue is focusing the attention of an incresing number of physicists all over the world. Among the possible alternatives in order to explain what as been named the "Mystery of the Millennium" are the so-called Modified…
This paper briefly reviews past, current, and future efforts to image black holes in the radio regime. Black holes seem like mystical objects, but they are an integral part of current astrophysics and are at the center of attempts to unify…