scholarly journals Black Holes as Possible Dark Matter

2021 ◽  
Author(s):  
Aloke Kumar Sinha
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dark Matter ◽  
Hawking Radiation ◽  
The Other ◽  
Theoretical Development ◽  
Complete Theory ◽  
Quantum Mechanical ◽  
Gravitational Effects ◽  
Mechanical Nature

Black holes and Dark matter are two fascinating things that are known very little. They may have non gravitational interactions, but those are definitely extremely feeble in comparison to their gravitational interactions. Nowadays some people think that one may contain the other. In this chapter we will see that some black holes may contain the dark matter. These black holes decay under Hawking radiation, but do not vanish completely. They produce stable end states due to both quantum gravitational effects and thermodynamic reasons. These end states are the replicas of what we call dark matter. We will develop the complete theory for decay of such black holes, starting from some scheme independent assumptions for the quantum mechanical nature of the black holes. We will then consider explicit examples of some black holes to show that they indeed produce replicas of dark matter at their end states. Thus this chapter is going to be a manuscript for theoretical development of black hole decay from a quantum mechanical perspective and its consequences for producing replicas of dark matter.

scholarly journals Oscillating Universe with a Quantized Black Hole

2021 ◽  
Author(s):  
Sascha Kulas
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dark Matter ◽  
Scalar Field ◽  
Vacuum Energy ◽  
Casimir Effect ◽  
Phenomenological Approach ◽  
The Other ◽  
Universe Model ◽  
Energy Field

In cosmology dark energy and dark matter are included in the CDM model, but they are still completely unknown. On the other hand the trans-Planckian problem leads to unlikely high photon energies for black holes. We introduce a model with quantized black hole matter. This minimizes the trans- Planckian problem extremely and leads to a scalar field in the oscillating universe model. We show that the scalar field has the same characteristics as a vacuum energy field and leads to the same Casimir effect. Shortly after the beginning of the big bounce this field decays locally and leads to the production of dark matter. In this model no inflation theory is needed. We emphasize that this model is mainly a phenomenological approach with the aim of new impetus to the discussion.

scholarly journals Black Hole - A Beginning, not the End

2021 ◽  
Vol 9 (VI) ◽  
pp. 1524-1525
Author(s):  
Purujit Malik
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dark Matter ◽  
Quantum Mechanics ◽  
General Theory ◽  
Hawking Radiation ◽  
Black Body ◽  
Physical Aspect ◽  
Theory Of Relativity ◽  
General Theory Of Relativity

A black hole is a region of space from which nothing, not even light, can escape. According to the general theory of relativity[2], it starts existing when spacetime gets curved by a huge mass. There is a sphere around the black hole. If something goes inside the sphere, it can not leave. This sphere is called the event horizon. A black hole is black because it absorbs all the light that hits it. It reflects nothing, just like a perfect black body in thermodynamics. Under quantum mechanics, black holes have a temperature and emit Hawking radiation, which makes them slowly get smaller.Because black holes are very hard to see, people trying to see them look for them by the way they affect other things near them. The place where there is a black hole can be found by tracking the movement of stars that orbit somewhere in space. Or people can find it when gas falls into a black hole, because the gas heats up and is very bright[1].However besides all these theories we still do not know what a black hole and dark matter is because all these theories rely on the much physical aspect of things and not on a unified understanding of creation.

scholarly journals BLACK HOLES REMNANTS IN EXTRA DIMENSIONS AND DARK MATTER

2006 ◽  
Vol 21 (23n24) ◽  
pp. 4979-4992 ◽  
Author(s):  
KOUROSH NOZARI ◽  
S. HAMID MEHDIPOUR
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dark Matter ◽  
Extra Dimensions ◽  
Large Extra Dimensions ◽  
Generalized Uncertainty Principle ◽  
Black Hole Thermodynamics ◽  
Gravitational Effects ◽  
Model Universe ◽  
Suitable Framework

Bekenstein–Hawking formalism of black hole thermodynamics should be modified to incorporate quantum gravitational effects. Generalized Uncertainty Principle (GUP) provides a suitable framework to perform such modifications. In this paper, we consider a general form of GUP to find black hole thermodynamics in a model universe with large extra dimensions. We will show that black holes radiate mainly in the four-dimensional brane. Existence of black holes remnants as a possible candidate for dark matter is discussed.

Fluctuating quasi-stable quantum-charged rotating black holes

2020 ◽  
Vol 35 (16) ◽  
pp. 2050136
Author(s):  
Aloke Kumar Sinha
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Quantum Mechanical ◽  
Thermal Bath ◽  
Dimensional Spacetime ◽  
Stable Quantum ◽  
Derivatives Of ◽  
The Universe ◽  
Partial Fulfillment ◽  
Mechanical Nature

We are engaged in studying thermodynamics of black holes from quantum mechanical perspective and already have published a series of papers. We first showed, based on certain assumptions for quantum mechanical nature of black holes, that they can be thought to be immersed in a thermal bath, i.e. rest of the universe. Of course, this consideration is required to study the thermodynamics of the black holes. We were able to find out the conditions of thermal stability for a black hole with arbitrary number of hairs in arbitrary dimensional spacetime. They came in form of a series of inequalities, connecting second-order derivatives of black hole mass with respect to its area and all the hairs. We then introduced the concept of “Quasi stability”, based on partial fulfillment of stability criteria, for thermally decaying black holes. We had also calculated the fluctuations for different hairs of a stable black hole. In this paper, we extend this calculation for charged rotating quasi-stable black holes. These fluctuations are interestingly found to be similar to that of stable black holes in certain aspects.

scholarly journals Hawking Radiation-Quasinormal Modes Correspondence for Large AdS Black Holes

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Dao-Quan Sun ◽  
Zi-Liang Wang ◽  
Miao He ◽  
Xian-Ru Hu ◽  
Jian-Bo Deng
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Effective Mass ◽  
Effective Temperature ◽  
Hawking Radiation ◽  
Radiation Spectrum ◽  
Quasinormal Modes ◽  
The Other ◽  
Five Dimensions ◽  
Ads Black Holes

It is well-known that the nonstrictly thermal character of the Hawking radiation spectrum generates a natural correspondence between Hawking radiation and black hole quasinormal modes. This main issue has been analyzed in the framework of Schwarzschild black holes, Kerr black holes, and nonextremal Reissner-Nordstrom black holes. In this paper, by introducing the effective temperature, we reanalyze the nonstrictly thermal character of large AdS black holes. The results show that the effective mass corresponding to the effective temperature is approximatively the average one in any dimension. And the other effective quantities can also be obtained. Based on the known forms of frequency in quasinormal modes, we reanalyze the asymptotic frequencies of the large AdS black hole in three and five dimensions. Then we get the formulas of the Bekenstein-Hawking entropy and the horizon’s area quantization with functions of the quantum “overtone” number n.

scholarly journals Oscillating Universe with a Quantized Black Hole

2021 ◽  
Author(s):  
Sascha Kulas
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dark Matter ◽  
Scalar Field ◽  
Vacuum Energy ◽  
Casimir Effect ◽  
Phenomenological Approach ◽  
The Other ◽  
Universe Model ◽  
Energy Field

In cosmology dark energy and dark matter are included in the CDM model, but they are still completely unknown. On the other hand the trans-Planckian problem leads to unlikely high photon energies for black holes. We introduce a model with quantized black hole matter. This minimizes the trans- Planckian problem extremely and leads to a scalar field in the oscillating universe model. We show that the scalar field has the same characteristics as a vacuum energy field and leads to the same Casimir effect. Shortly after the beginning of the big bounce this field decays locally and leads to the production of dark matter. In this model no inflation theory is needed. We emphasize that this model is mainly a phenomenological approach with the aim of new impetus to the discussion.

scholarly journals Bounds on warm dark matter from Schwarzschild primordial black holes

2021 ◽  
Vol 136 (2) ◽  
Author(s):  
Jérémy Auffinger ◽  
Isabella Masina ◽  
Giorgio Orlando
Keyword(s):  
Beyond Standard Model ◽  
Black Holes ◽  
Black Hole ◽  
Dark Matter ◽  
Energy Density ◽  
The Other ◽  
Primordial Black Hole ◽  
Primordial Black Holes ◽  
Hole Energy ◽  
Upper Limits

AbstractWe consider light dark matter candidates originated from the evaporation of Schwarzschild primordial black holes, with masses in the range $$10^{-5}$$ 10 - 5 –$$10^9$$ 10 9 g. These candidates are beyond standard model particles with negligible couplings to the other particles, so that they interact only gravitationally. Belonging to the category of warm dark matter, they nevertheless spoil structure formation, with a softer impact for increasing values of the candidate spin. Requiring such candidates to fully account for the observed dark matter, we find that the scenario of black hole domination is ruled out for all spin values up to 2. For the scenario of radiation domination, we derive upper limits on the parameter $$\beta $$ β (the primordial black hole energy density at formation over the radiation one), which are less stringent the higher the candidate spin is.

scholarly journals Islands and stretched horizon

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Yoshinori Matsuo
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Hawking Radiation ◽  
Entanglement Entropy ◽  
Total System ◽  
Island Rule ◽  
Asymptotically Flat ◽  
Flat Spacetime ◽  
Ads Spacetime ◽  
Hole Geometry

Abstract Recently it was proposed that the entanglement entropy of the Hawking radiation contains the information of a region including the interior of the event horizon, which is called “island.” In studies of the entanglement entropy of the Hawking radiation, the total system in the black hole geometry is separated into the Hawking radiation and black hole. In this paper, we study the entanglement entropy of the black hole in the asymptotically flat Schwarzschild spacetime. Consistency with the island rule for the Hawking radiation implies that the information of the black hole is located in a different region than the island. We found an instability of the island in the calculation of the entanglement entropy of the region outside a surface near the horizon. This implies that the region contains all the information of the total system and the information of the black hole is localized on the surface. Thus the surface would be interpreted as the stretched horizon. This structure also resembles black holes in the AdS spacetime with an auxiliary flat spacetime, where the information of the black hole is localized at the interface between the AdS spacetime and the flat spacetime.

scholarly journals Islands and Page curves of Reissner-Nordström black holes

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Xuanhua Wang ◽  
Ran Li ◽  
Jin Wang
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Hawking Radiation ◽  
Entanglement Entropy ◽  
Additional Term ◽  
Current Case ◽  
Information Paradox ◽  
Extremal Surface ◽  
Four Dimensions ◽  
Black Hole Information

Abstract We apply the recently proposed quantum extremal surface construction to calculate the Page curve of the eternal Reissner-Nordström black holes in four dimensions ignoring the backreaction and the greybody factor. Without the island, the entropy of Hawking radiation grows linearly with time, which results in the information paradox for the eternal black holes. By extremizing the generalized entropy that allows the contributions from the island, we find that the island extends to the outside the horizon of the Reissner-Nordström black hole. When taking the effect of the islands into account, it is shown that the entanglement entropy of Hawking radiation at late times for a given region far from the black hole horizon reproduces the Bekenstein-Hawking entropy of the Reissner-Nordström black hole with an additional term representing the effect of the matter fields. The result is consistent with the finiteness of the entanglement entropy for the radiation from an eternal black hole. This facilitates to address the black hole information paradox issue in the current case under the above-mentioned approximations.

scholarly journals THERMODYNAMICS OF CONSTANT CURVATURE BLACK HOLES THROUGH SEMICLASSICAL TUNNELING

2011 ◽  
Vol 26 (13) ◽  
pp. 937-947 ◽  
Author(s):  
ALEXANDRE YALE
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Constant Curvature ◽  
Hawking Radiation ◽  
Emission Rate ◽  
Yang Mills ◽  
Fermion Fields ◽  
Tunneling Method ◽  
Semiclassical Tunneling ◽  
Algorithmic Procedure

We study the semiclassical tunneling of scalar and fermion fields from the horizon of a Constant Curvature Black Hole, which is locally AdS and whose five-dimensional analogue is dual to [Formula: see text] super-Yang–Mills. In particular, we highlight the strong reliance of the tunneling method for Hawking radiation on near-horizon symmetries, a fact often hidden behind the algorithmic procedure with which the tunneling approach tends to be used. We ultimately calculate the emission rate of scalars and fermions, and hence the black hole's Hawking temperature.

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