Related papers: Small, dark, and heavy: But is it a black hole?
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…
Recently wide publicity has been given to a claim by T. Vachaspati that "black holes do not exist", that the objects known as black holes in astrophysics should rather be called "black stars" and they not only do not have event horizons but…
Black holes merge together different field of physics. From General Relativity over thermodynamics and quantum field theory, they do now also reach into the regime of particle and collider physics. In the presence of additional compactified…
Black holes harbor a spacetime singularity of infinite curvature, where classical spacetime physics breaks down, and current theory cannot predict what will happen. However, the singularity is invisible from the outside because strong…
This paper reviews the X-ray, optical, radio and IR observations of galactic X-ray binaries suspected to contain black hole compact objects, with particular emphasis on the supporting dynamical evidence.
The article summarizes the observational evidence for the existence of massive black holes, as well as the current knowledge about their abundance, their mass and spin distributions, and their cosmic evolution within and together with their…
There have been proposals that primordial black hole remnants (BHRs) are the dark matter, but the idea is somewhat vague. We argue here first that the generalized uncertainty principle (GUP) may prevent black holes from evaporating…
A succinct summary is given of the problem of reconciling observation of black hole-like objects with quantum mechanics. If quantum black holes behave like subsystems, and also decay, their information must be transferred to their…
We argue for black holes do not represent a strict consequence of general relativity.
Observations in the optical, in X-rays, and gravitational lensing of galaxies, clusters of galaxies, and large-scale structure are beginning to provide clues to the dark matter problem. I review the impact of these observations on some of…
In this chapter, we introduce the concept of a black hole (BH) and recount the initial theoretical predictions. We then review the possible types of BHs in nature, from primordial, to stellar-mass, to supermassive BHs. Finally, we focus on…
Classical black holes and event horizons are highly non-local objects, defined in relation to the causal past of future null infinity. Alternative, quasilocal characterizations of black holes are often used in mathematical, quantum, and…
Two interesting hypotheses about black holes have been proposed. The older one states that microscopic black holes can be accountable for the observed dark matter density. The newer one states that black holes are coupled to the expansion…
Since a black hole does not emit light from its interior, nor does it have a surface on which light from nearby sources can be reflected, observational study of black hole physics requires observing the gravitational impact of the black…
It is thought that the final product of the gravitational collapse is a Kerr black hole and astronomers have discovered several good astrophysical candidates. While there is some indirect evidence suggesting that the latter have an event…
The nature of dark matter is still an open problem. The simplest assumption is that gravity is the only force coupled certainly to dark matter and thus the micro black holes could be a viable candidate. We investigated the possibility of…
We describe the possible forms of black hole images, viewed by a distant observer. These images are numerically calculated basing on general relativity and equations of motion in the Kerr-Newman metric. Black hole image is a gravitationally…
We examine the properties of nearly extremal black holes produced by gravitational collapse. It is shown that an observer who crosses the black hole horizon at late times rapidly encounters a singularity.
Black holes are extreme outcomes of General Relativity, and can form through a variety of ways, including gravitational collapse of massive stars, or quantum fluctuations in the early universe. Here, we ask the question of whether they can…
We define different notions of black holes, event horizons and Killing horizons for a general time-oriented manifold $(M,g)$ extending previous notions but without the assumption of asymptotical flatness. The notions of 'horizon' are always…