scholarly journals The Progress of Black Holes: Principles & Physical Detection Technology

2021 ◽  
Vol 2083 (2) ◽  
pp. 022047
Author(s):  
Tianyi Chen ◽  
Shutong Ge ◽  
Jiahui Li ◽  
Xuheng Ma
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Recent Progress ◽  
Mathematical Methods ◽  
Theoretical Understanding ◽  
Detection Technology ◽  
Arbitrary Dimensions ◽  
The 19Th Century ◽  
The Universe ◽  
Shed Light

Abstract Humans have been trying to explain black holes since the 19th century, using theoretical understanding and observations of the universe. Incandescent body thermal radiation has been the focus of extensive theoretical and experimental research for over a century. This paper will discuss the concept of a black hole and use information retrieval to generate a panoramic image of it. The content illustrates black holes from three different perspectives: description of black holes using mathematical methods and data, models, and detection. A black hole is a controversial object, and no one knows for sure what it is. Indeed, multiple numerical simulations have been carried out to investigate the critical behaviors of black holes with various geometrical configurations in arbitrary dimensions. We will sum up the black hole knowledge so far and discuss the recent progress in terms of black hole exploration, i.e., shed light for future black holes model construction and detection.

scholarly journals Black Holes in the Universe

1998 ◽  
Vol 11 (1) ◽  
pp. 28-41
Author(s):  
I.D. Novikov
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Neutron Stars ◽  
Supernova Explosions ◽  
The Universe

Some 30 years ago very few scientists thought that black holes may really exist. Attention focussed on the black hole hypothesis after neutron stars had been discovered. It was rather surprising that astrophysicists immediately ‘welcomed’ black holes. They found their place not only in the remnants of supernova explosions but also in the nuclei of galaxies and quasars.

scholarly journals Symmetry and the Arrow of Time in Theoretical Black Hole Astrophysics

2015 ◽  
Vol 2015 ◽  
pp. 1-5
Author(s):  
David Garofalo
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Active Galactic Nuclei ◽  
Accretion Disks ◽  
Time Reversal ◽  
Large Scale ◽  
Galactic Nuclei ◽  
Arrow Of Time ◽  
Time Symmetry ◽  
The Universe

While the basic laws of physics seem time-reversal invariant, our understanding of the apparent irreversibility of the macroscopic world is well grounded in the notion of entropy. Because astrophysics deals with the largest structures in the Universe, one expects evidence there for the most pronounced entropic arrow of time. However, in recent theoretical astrophysics work it appears possible to identify constructs with time-reversal symmetry, which is puzzling in the large-scale realm especially because it involves the engines of powerful outflows in active galactic nuclei which deal with macroscopic constituents such as accretion disks, magnetic fields, and black holes. Nonetheless, the underlying theoretical structure from which this accreting black hole framework emerges displays a time-symmetric harmonic behavior, a feature reminiscent of basic and simple laws of physics. While we may expect such behavior for classical black holes due to their simplicity, manifestations of such symmetry on the scale of galaxies, instead, surprise. In fact, we identify a parallel between the astrophysical tug-of-war between accretion disks and jets in this model and the time symmetry-breaking of a simple overdamped harmonic oscillator. The validity of these theoretical ideas in combination with this unexpected parallel suggests that black holes are more influential in astrophysics than currently recognized and that black hole astrophysics is a more fundamental discipline.

scholarly journals Gas filaments of the cosmic web located around active galaxies in a protocluster

Science ◽  
2019 ◽  
Vol 366 (6461) ◽  
pp. 97-100 ◽  
Author(s):  
H. Umehata ◽  
M. Fumagalli ◽  
I. Smail ◽  
Y. Matsuda ◽  
A. M. Swinbank ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Star Formation ◽  
Ionizing Radiation ◽  
Rest Frame ◽  
Active Galaxies ◽  
Intergalactic Gas ◽  
Supermassive Black Hole ◽  
The Universe ◽  
Intense Star Formation

Cosmological simulations predict that the Universe contains a network of intergalactic gas filaments, within which galaxies form and evolve. However, the faintness of any emission from these filaments has limited tests of this prediction. We report the detection of rest-frame ultraviolet Lyman-α radiation from multiple filaments extending more than one megaparsec between galaxies within the SSA22 protocluster at a redshift of 3.1. Intense star formation and supermassive black-hole activity is occurring within the galaxies embedded in these structures, which are the likely sources of the elevated ionizing radiation powering the observed Lyman-α emission. Our observations map the gas in filamentary structures of the type thought to fuel the growth of galaxies and black holes in massive protoclusters.

The Odd Couple: Quasars & Black Holes

Daedalus ◽  
2014 ◽  
Vol 143 (4) ◽  
pp. 103-113 ◽  
Author(s):  
Scott Tremaine
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Solar System ◽  
Total Mass ◽  
Host Galaxy ◽  
The Sun ◽  
Central Black Hole ◽  
Frictional Forces ◽  
The Universe

Quasars emit more energy than any other object in the universe, yet are not much bigger than our solar system. Quasars are powered by giant black holes of up to ten billion (1010) times the mass of the sun. Their enormous luminosities are the result of frictional forces acting upon matter as it spirals toward the black hole, heating the gas until it glows. We also believe that black holes of one million to ten billion solar masses – dead quasars – are present at the centers of most galaxies, including our own. The mass of the central black hole appears to be closely related to other properties of its host galaxy, such as the total mass in stars, but the origin of this relation and the role that black holes play in the formation of galaxies are still mysteries.

scholarly journals EXTREMAL BLACK HOLES, HOLOGRAPHY AND COARSE GRAINING

2011 ◽  
Vol 26 (12) ◽  
pp. 1903-1971 ◽  
Author(s):  
JOAN SIMON
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Degrees Of Freedom ◽  
Recent Progress ◽  
Coarse Graining ◽  
Extremal Black Hole ◽  
Holographic Screens ◽  
Dynamical Description ◽  
Gravitational Thermodynamics ◽  
Extremal Black Holes

I review some of the concepts at the crossroads of gravitational thermodynamics, holography and quantum mechanics. First, the origin of gravitational thermodynamics due to coarse graining of quantum information is exemplified using the half-BPS sector of [Formula: see text] SYM and its LLM description in type IIB supergravity. The notion of black holes as effective geometries, its relation to the fuzzball programme and some of the puzzles raising for large black holes are discussed. Second, I review recent progress for extremal black holes, both microscopically, discussing a constituent model for stationary extremal non-BPS black holes, and semiclassically, discussing the extremal black hole/CFT conjecture. The latter is examined from the AdS3/CFT2 perspective. Third, I review the importance of the holographic principle to encode nonlocal gravity features allowing us to relate the gravitational physics of local observers with thermodynamics and the role causality plays in these arguments by identifying horizons (screens) as diathermic walls. I speculate with the emergence of an approximate CFT in the deep IR close to any horizon and its relation with an effective dynamical description of the degrees of freedom living on these holographic screens.

scholarly journals A Note on the Observational Evidence for the Existence of Event Horizons in Astrophysical Black Hole Candidates

2013 ◽  
Vol 2013 ◽  
pp. 1-4 ◽  
Author(s):  
Cosimo Bambi
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Electromagnetic Radiation ◽  
Event Horizon ◽  
Observational Evidence ◽  
Short Paper ◽  
Event Horizons ◽  
Internal Region ◽  
The Universe ◽  
Black Hole Candidates

Black holes have the peculiar and intriguing property of having an event horizon, a one-way membrane causally separating their internal region from the rest of the Universe. Today, astrophysical observations provide some evidence for the existence of event horizons in astrophysical black hole candidates. In this short paper, I compare the constraint we can infer from the nonobservation of electromagnetic radiation from the putative surface of these objects with the bound coming from the ergoregion instability, pointing out the respective assumptions and limitations.

Primordial black holes and the observable features of the universe

2015 ◽  
Vol 24 (13) ◽  
pp. 1545005 ◽  
Author(s):  
K. M. Belotsky ◽  
A. A. Kirillov ◽  
S. G. Rubin
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dark Matter ◽  
Galactic Center ◽  
Mass Range ◽  
Primordial Black Holes ◽  
Simultaneous Solution ◽  
Supermassive Black Hole ◽  
Range Distribution ◽  
The Universe

Here, we briefly discuss the possibility to solve simultaneously with primordial black holes (PBHs) the problems of dark matter (DM), reionization of the universe, origin of positron line from Galactic center and supermassive black hole (BH) in it. Discussed scenario can naturally lead to a multiple-peak broad-mass-range distribution of PBHs in mass, which is necessary for simultaneous solution of the problems.

scholarly journals EVOLUTION OF PRIMORDIAL BLACK HOLE MASS SPECTRUM IN BRANS–DICKE THEORY

2013 ◽  
Vol 22 (05) ◽  
pp. 1350022 ◽  
Author(s):  
D. DWIVEDEE ◽  
B. NAYAK ◽  
L. P. SINGH
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Mass Spectrum ◽  
Energy Density ◽  
Analytic Solutions ◽  
Primordial Black Hole ◽  
Primordial Black Holes ◽  
Black Hole Mass ◽  
Linear And Nonlinear ◽  
The Universe

We investigate the evolution of primordial black hole mass spectrum by including both accretion of radiation and Hawking evaporation within Brans–Dicke (BD) cosmology in radiation-, matter- and vacuum-dominated eras. We also consider the effect of evaporation of primordial black holes on the expansion dynamics of the universe. The analytic solutions describing the energy density of the black holes in equilibrium with radiation are presented. We demonstrate that these solutions act as attractors for the system ensuring stability for both linear and nonlinear situations. We show, however, that inclusion of accretion of radiation delays the onset of this equilibrium in all radiation-, matter- and vacuum-dominated eras.

scholarly journals Cosmic cloaking of rich extra dimensions

2021 ◽  
Author(s):  
Aghil Alaee ◽  
Marcus Khuri ◽  
Hari Kunduri
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Extra Dimensions ◽  
Large Extra Dimensions ◽  
Dimensional Theory ◽  
Hoop Conjecture ◽  
Significant Size ◽  
The Universe ◽  
Lower Dimensional ◽  
Kaluza Klein

We present arguments that show why it is difficult to see rich extra dimensions in the universe. Conditions are found where significant size and variation of the extra dimensions in a Kaluza–Klein compactification lead to a black hole in the lower-dimensional theory. The idea is based on the hoop conjecture concerning black hole existence, as well as on the observation that dimensional reduction on macroscopically large, twisted, or highly dynamical extra dimensions contributes positively to the energy density in the lower-dimensional theory and can induce gravitational collapse. A threshold for the size is postulated on the order of [Formula: see text][Formula: see text]m, whereby extra dimensions of length above this level must lie inside black holes, thus cloaking them from the view of outside observers. The threshold depends on the size of the universe, leading to speculation that in the early stages of evolution truly macroscopic and large extra dimensions would have been visible.

scholarly journals The progress of mini black holes: principles and analytical astronomical observation techniques

2021 ◽  
Vol 2083 (2) ◽  
pp. 022040
Author(s):  
Jiatong Tan
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Astronomical Observation ◽  
Quantum Field ◽  
Prospective Development ◽  
Stephen Hawking ◽  
Mini Black Holes ◽  
Background Models ◽  
Shed Light

Abstract Mini-black hole (MBH) is a concept first proposed by Stephen Hawking in the 1970s. Normally, exploring MBHs will enhance the understanding of quantum theory and gravity theory as well as be helpful in predicting the configuration of the early universe. Based on information retrieval, this paper summarizes the progress of MBHs and takes three major aspects: background, models, practical methods for observations, and analysis. Specifically, the descriptive equations are derived, and different models are discussed separately. These results shed light on the prospective development of quantum field theorem, general relativity, and string theory.

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