Related papers: The Revival of White Holes as Small Bangs
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…
Because of the very definition of black holes --- no light escapes them and falling objects get infinitely faint when approaching --- it is impossible to ever prove that they exist. However, electromagnetic and gravitational-wave…
Current phenomenology suggests the presence of a compact baryon-poor energy source to cosmological gamma-ray bursts reacting to high-density matter. The association of short and long gamma-ray bursts with hyper- and suspended accretion onto…
Black holes are defined as a region in spacetime where gravity is so strong that particles and electromagnetic radiation cannot escape. According to their mass, they are classified into three types: stellar-mass black holes,…
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…
Our understanding of space and time is probed to its depths by black holes. These objects, which appear as a natural consequence of general relativity, provide a powerful analytical tool able to examine macroscopic and microscopic…
The origin of cosmic gamma-ray bursts remains one of the most intriguing puzzles in astronomy. We suggest that purely general relativistic effects in the collapse of massive stars could account for these bursts. The late formation of closed…
Gamma-ray bursts are associated with catastrophic cosmic events. They appear when a new black hole, created after the explosion of a massive star or the merger of two compact stars, quickly accretes the matter around it and ejects a…
Stars that are collapsing toward forming a black hole but are frozen near the Schwarzschild horizon are termed "black stars". Collisions of black stars, in contrast to black hole collisions, may be sources of gamma ray bursts, whose basic…
The mathematical simplicity of black holes, combined with their links to some of the most energetic events in the universe, means that black holes are key objects for fundamental physics and astrophysics. Until recently, it was generally…
The recent observation of gravitational waves confirms one of the most interesting predictions in general relativity: the black holes. Because the gravitational waves detected by LIGO fit very well within general relativity as a phenomenon…
Black holes are perhaps the most strange and fascinating objects known to exist in the universe. Our understanding of space and time is pushed to its limits by the extreme conditions found in these objects. They can be used as natural…
The formation of supermassive black holes through the gravitational collapse of supermassive objects ($M \ga 10^4 M_\odot$) has been proposed as a source of cosmological gamma-ray bursts. The major advantage of this model is that such…
Black and white holes play remarkably contrasting roles in general relativity versus observational astrophysics. While there is overwhelming observational evidence for the existence of compact objects that are "cold, dark, and heavy", which…
Supermassive black holes have generally been recognized as the most destructive force in nature. But in recent years, they have undergone a dramatic shift in paradigm. These objects may have been critical to the formation of structure in…
Black holes are extreme expressions of gravity. Their existence is predicted by Einstein's theory of general relativity and is supported by observations. Black holes obey quantum mechanics and evaporate spontaneously. Here it is shown that…
There is strong evidence for the existence of black holes(BHs) in some X-ray binaries and most galatic nuclei, based on different measuremental approaches, but black holes aren't finally identified for the lack of very firm observational…
We use recent results in binary stellar evolution to argue that binaries with at least one black hole dominate the rate of compact-object mergers. Two phenomena generally attributable to such mergers, gamma-ray bursts and gravity-wave…
Quantum tunneling of a black hole into a white hole provides a model for the full life cycle of a black hole. The white hole acts as a long-lived remnant, solving the black-hole information paradox. The remnant solution of the paradox has…
The gravitational collapse of a spherically symmetric star, made of a dust fluid, $\rho_{DM}$, in a background of dark energy, $p = w\rho,\; (w < -1/3)$, is studied. It is found that when only dark energy is present, black holes are {\em…