scholarly journals Evolution of primordial black hole spin due to Hawking radiation

2020 ◽  
Vol 494 (1) ◽  
pp. 1257-1262 ◽  
Author(s):  
Alexandre Arbey ◽  
Jérémy Auffinger ◽  
Joseph Silk
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
High Spin ◽  
Hawking Radiation ◽  
Primordial Black Hole ◽  
Mass Limit ◽  
Lower Mass ◽  
Thin Disc ◽  
Kerr Black Holes ◽  
Lower Mass Limit

ABSTRACT Near extremal Kerr black holes (BHs) are subject to the Thorne limit $a\lt a^*_{\rm lim}=0.998$ in the case of thin disc accretion, or some generalized version of this in other disc geometries. However, any limit that differs from the thermodynamics limit a* < 1 can in principle be evaded in other astrophysical configurations, and in particular if the near extremal BHs are primordial and subject to evaporation by Hawking radiation only. We derive the lower mass limit above which Hawking radiation is slow enough so that a primordial black hole with a spin initially above some generalized Thorne limit can still be above this limit today. Thus, we point out that the observation of Kerr BHs with extremely high spin should be a hint of either exotic astrophysical mechanisms or primordial origin.

Observational lower mass limit for black hole formation derived from massive X-ray binaries

Nature ◽  
1984 ◽  
Vol 309 (5969) ◽  
pp. 598-600 ◽  
Author(s):  
E. P. J. van den Heuvel ◽  
G. M. H. J. Habets
Keyword(s):  
Black Hole ◽  
Mass Limit ◽  
Hole Formation ◽  
Lower Mass ◽  
X Ray ◽  
Black Hole Formation ◽  
X Ray Binaries ◽  
Lower Mass Limit

Black holes

2018 ◽  
Author(s):  
Michael Kachelriess
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Thermal Radiation ◽  
Event Horizon ◽  
Hawking Radiation ◽  
Information Paradox ◽  
Classical Physics ◽  
Physical Singularity ◽  
Kerr Black Holes ◽  
Classical Picture

Black holes are introduced as solutions of Einsteins equations contain-ing a physical singularity covered by an event horizon. The properties of Schwarzschild and of Kerr black holes are examined. It is demonstrated that the event horizon of a black hole can only increase within classical physics. However, the event horizon is an infinite redshift surface and emits in the semi-classical picture thermal radiation. This Hawking radiation leads in turn to the information paradox.

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 The Merger Rate of Black Holes in a Primordial Black Hole Cluster

Physics ◽  
2021 ◽  
Vol 3 (2) ◽  
pp. 372-378
Author(s):  
Viktor D. Stasenko ◽  
Alexander A. Kirillov
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Mass Spectrum ◽  
Star Clusters ◽  
Primordial Black Hole ◽  
Primordial Black Holes ◽  
Central Black Hole ◽  
Solar Mass ◽  
Merger Rate

In this paper, the merger rate of black holes in a cluster of primordial black holes (PBHs) is investigated. The clusters have characteristics close to those of typical globular star clusters. A cluster that has a wide mass spectrum ranging from 10−2 to 10M⊙ (Solar mass) and contains a massive central black hole of the mass M•=103M⊙ is considered. It is shown that in the process of the evolution of cluster, the merger rate changed significantly, and by now, the PBH clusters have passed the stage of active merging of the black holes inside them.

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.

On Primordial Black Holes and secondary gravitational waves generated from inflation with solo/multi-bumpy potential

2021 ◽  
Author(s):  
Rui feng Zheng ◽  
Jia ming Shi ◽  
Taotao Qiu
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Gravitational Waves ◽  
Power Spectra ◽  
Small Scale ◽  
Primordial Black Hole ◽  
Primordial Black Holes ◽  
Slow Roll ◽  
Spherical Collapse ◽  
Scalar Perturbations

Abstract It is well known that primordial black hole (PBH) can be generated in inflation process of the early universe, especially when the inflaton field has some non-trivial features that could break the slow-roll condition. In this paper, we investigate a toy model of inflation with bumpy potential, which has one or several bumps. We found that potential with multi-bump can give rise to power spectra with multi peaks in small-scale region, which can in turn predict the generation of primordial black holes in various mass ranges. We also consider the two possibilities of PBH formation by spherical collapse and elliptical collapse. And discusses the scalar-induced gravitational waves (SIGWs) generated by the second-order scalar perturbations.

scholarly journals Fermat’s principle in black-hole spacetimes

2018 ◽  
Vol 27 (14) ◽  
pp. 1847025 ◽  
Author(s):  
Shahar Hod
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Black Hole Spacetimes ◽  
Fermat’S Principle ◽  
Kerr Black Holes ◽  
Fermat's Principle ◽  
Asymptotic Observers

Black-hole spacetimes are known to possess closed light rings. We here present a remarkably compact theorem which reveals the physically intriguing fact that these unique null circular geodesics provide the fastest way, as measured by asymptotic observers, to circle around spinning Kerr black holes.

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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