scholarly journals Thermodynamics of non-commutative scalar-tensor-vector gravity black holes

2020 ◽  
pp. 2150024
Author(s):  
Sara Saghafi ◽  
Kourosh Nozari ◽  
Milad Hajebrahimi
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Coherent State ◽  
Thermodynamic Stability ◽  
Modified Gravity ◽  
Final Stage ◽  
Tunneling Mechanism ◽  
Massive Particles

In this paper, we analyze the thermodynamic stability of Schwarzschild Modified Gravity (MOG) black holes in a non-commutative framework. We show that, unlike a commutative MOG black hole, in the coherent state picture of non-commutativity MOG black holes are thermodynamically stable. At the final stage of evaporation a stable remnant with zero temperatures and finite entropy is left in this non-commutative framework. Also, we consider the Parikh–Wilczek tunneling mechanism of massive particles from non-commutative MOG black holes and demonstrate that information leaks out of non-commutative MOG black holes in the form of some non-thermal correlations.

scholarly journals Two New Possible Mechanisms of Supernova-Like Explosions

2005 ◽  
Vol 192 ◽  
pp. 263-268
Author(s):  
V.V. Tikhomirov ◽  
S.E. Yuralevich
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Neutron Stars ◽  
Final Stage ◽  
White Dwarfs ◽  
Primordial Black Holes ◽  
Considerable Part ◽  
Nuclear Burning ◽  
Urca Process ◽  
Hubble Time

SummaryPrimordial black holes (PBHs) of microscopical size can completely absorb neutron stars (NSs) and white dwarfs (WDs) for less than the Hubble time. NS absorption is accompanied by inverse URCA process giving rise to emission of antineutrino. However considerable part of these antineutrino fails to escape NS being drawn into the growing black hole by accreting NS matter. The final stage of dense WD absorption is accompanied by 1051 erg neutrino burst able to ignite nuclear burning giving rise to supernova-like WD explosion.

scholarly journals Proton decay and the quantum structure of space–time

2019 ◽  
Vol 97 (12) ◽  
pp. 1317-1322
Author(s):  
Abeer Al-Modlej ◽  
Salwa Alsaleh ◽  
Hassan Alshal ◽  
Ahmed Farag Ali
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Coherent State ◽  
Dimensional Space ◽  
Space Time ◽  
Noncommutative Space ◽  
Quantum Structure ◽  
Dimensional Space Time ◽  
Proton Lifetime ◽  
Virtual Black Holes

Virtual black holes in noncommutative space–time are investigated using coordinate coherent state formalism such that the event horizon of a black hole is manipulated by smearing it with a Gaussian of width [Formula: see text], where θ is the noncommutativity parameter. Proton lifetime, the main associated phenomenology of the noncommutative virtual black holes, has been studied, first in four-dimensional space–time and then generalized to D dimensions. The lifetime depends on θ and the number of space–time dimensions such that it emphasizes on the measurement of proton lifetime as a potential probe for the microstructure of space–time.

scholarly journals Global embeddings and hydrodynamic properties of Kerr black hole

2016 ◽  
Vol 31 (35) ◽  
pp. 1650204
Author(s):  
Soon-Tae Hong
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Equatorial Plane ◽  
Kerr Black Hole ◽  
Kerr Spacetime ◽  
Stable Circular Orbit ◽  
Massive Particles ◽  
Flat Embedding ◽  
Bound Orbits ◽  
The Impact

In the presence of a rotating Kerr black hole, we investigate hydrodynamics of the massive particles and massless photons to construct relations among number density, pressure and internal energy density of the massive particles and photons around the rotating Kerr black hole and to study an accretion onto the black hole. On equatorial plane of the Kerr black hole, we investigate the bound orbits of the massive particles and photons around the black hole to produce their radial, azimuthal and precession frequencies. With these frequencies, we study the black holes GRO J1655-40 and 4U 1543-47 to explicitly obtain the radial, azimuthal and precession frequencies of the massive particles in the flow of perfect fluid. We next consider the massive particles in the stable circular orbit of radius of 1.0 ly around the supernovas SN 1979C, SN 1987A and SN 2213-1745 in the Kerr curved spacetime, and around the potential supermassive Schwarzschild black holes M87, NGC 3115, NGC 4594, NGC 3377, NGC 4258, M31, M32 and Galatic center, to estimate their radial and azimuthal frequencies, which are shown to be the same results as those in no precession motion. The photon unstable orbit is also discussed in terms of the impact parameter of the photon trajectory. Finally, on the equatorial plane of the Kerr black hole, we construct the global flat embedding structures possessing (9 + 3) dimensionalities outside and inside the event horizon of the rotating Kerr black hole. Moreover, on the plane, we investigate the warp products of the Kerr spacetime.

Revisit on the thermodynamic stability of the noncommutative Schwarzschild black hole

2017 ◽  
Vol 26 (03) ◽  
pp. 1750018 ◽  
Author(s):  
Meng-Sen Ma ◽  
Yan-Song Liu ◽  
Huai-Fan Li
Keyword(s):  
Black Holes ◽  
Heat Capacity ◽  
Black Hole ◽  
Thermodynamic Stability ◽  
Black Hole Thermodynamics ◽  
Positive Temperature ◽  
Schwarzschild Black Hole ◽  
Horizon Thermodynamics ◽  
Thermodynamics Of Black Holes ◽  
Thermodynamic Curvature

In two frameworks, we discuss the thermodynamic stability of noncommutative geometry inspired Schwarzschild black hole (NCSBH). Under the horizon thermodynamics of black holes, we show that the NCSBH cannot be thermodynamically stable if requiring positive temperature. We note the inconsistency in the work of Larrañaga et al. and propose an effective first law of black hole thermodynamics for the NCSBH to eliminate the inconsistency. Based on the effective first law, we recalculate the heat capacity and the thermodynamic curvature by means of geometrothermodynamics (GTD) to revisit the thermodynamic stability.

Observing the shadow of modified gravity black hole

2017 ◽  
Vol 26 (14) ◽  
pp. 1750156 ◽  
Author(s):  
Ahmed Alhamzawi
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Modified Gravity ◽  
Kerr Black Hole ◽  
Naked Singularity ◽  
Gravity Models ◽  
Considerable Contribution ◽  
Rotating Black Holes ◽  
Shadow Cast ◽  
Modified Gravity Models

A study of the shadow cast by rotating black holes in different models of modified gravity is presented. It is shown that the size of the shadow cast depends on the modified gravity model used. The distortions of the shadow cast by modified gravity black holes are investigated and the effects are compared with the distortions cast by Kerr black hole. The shadow of a rotating black hole in modified gravity is found to be similar to the shadow cast by Kerr black hole but with different sizes and distortion effects. The naked singularity by rotating modified gravity black hole is discussed. Finally, it is shown that some modified gravity models can present a considerable contribution to the size of black hole shadow.

scholarly journals Topological black holes in mimetic gravity

2021 ◽  
Author(s):  
Ahmad Sheykhi ◽  
Saskia Grunau
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dark Matter ◽  
Einstein Gravity ◽  
Rotation Curves ◽  
Negative Constant ◽  
Massive Particles ◽  
Bound Orbits ◽  
Mimetic Gravity ◽  
Black Hole Solutions

In this paper, we construct some new classes of topological black hole solutions in the context of mimetic gravity and investigate their properties. We study the uncharged and charged black holes, separately. We find the following novel results: (i) In the absence of a potential for the mimetic field, black hole solutions can address the flat rotation curves of spiral galaxies and alleviate the dark matter problem without invoking particle dark matter. Thus, mimetic gravity can provide a theoretical background for understanding flat galactic rotation curves through modifying Schwarzschild space–time. (ii) We also investigate the casual structure and physical properties of the solutions. We observe that in the absence of a potential, our solutions are not asymptotically flat, while in the presence of a negative constant potential for the mimetic field, the solutions are asymptotically anti-de Sitter (AdS). (iii) Finally, we explore the motion of massless and massive particles and give a list of the types of orbits. We study the differences of geodesic motion in the Einstein gravity and in mimetic gravity. In contrast to the Einstein gravity, massive particles always move on bound orbits and cannot escape the black hole in mimetic gravity. Furthermore, we find stable bound orbits for massless particles.

scholarly journals Effect of Quantum Gravity on the Stability of Black Holes

Symmetry ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 631 ◽  
Author(s):  
Riasat Ali ◽  
Kazuharu Bamba ◽  
Syed Asif Ali Shah
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Quantum Gravity ◽  
Gravitational Interaction ◽  
Tunneling Probability ◽  
Back Reaction ◽  
Massive Vector ◽  
Tunneling Mechanism ◽  
Quantum Gravity Effect ◽  
The Stability

We investigate the massive vector field equation with the WKB approximation. The tunneling mechanism of charged bosons from the gauged super-gravity black hole is observed. It is shown that the appropriate radiation consistent with black holes can be obtained in general under the condition that back reaction of the emitted charged particle with self-gravitational interaction is neglected. The computed temperatures are dependant on the geometry of black hole and quantum gravity. We also explore the corrections to the charged bosons by analyzing tunneling probability, the emission radiation by taking quantum gravity into consideration and the conservation of charge and energy. Furthermore, we study the quantum gravity effect on radiation and discuss the instability and stability of black hole.

scholarly journals Morphological evolution of supermassive black hole merger hosts and multimessenger signatures

2021 ◽  
Vol 503 (3) ◽  
pp. 3629-3642
Author(s):  
Colin DeGraf ◽  
Debora Sijacki ◽  
Tiziana Di Matteo ◽  
Kelly Holley-Bockelmann ◽  
Greg Snyder ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Star Formation ◽  
Morphological Evolution ◽  
Full Range ◽  
High Mass ◽  
Morphological Evidence ◽  
Galaxy Mergers ◽  
Host Galaxies ◽  
Supermassive Black Hole

ABSTRACT With projects such as Laser Interferometer Space Antenna (LISA) and Pulsar Timing Arrays (PTAs) expected to detect gravitational waves from supermassive black hole mergers in the near future, it is key that we understand what we expect those detections to be, and maximize what we can learn from them. To address this, we study the mergers of supermassive black holes in the Illustris simulation, the overall rate of mergers, and the correlation between merging black holes and their host galaxies. We find these mergers occur in typical galaxies along the MBH−M* relation, and that between LISA and PTAs we expect to probe the full range of galaxy masses. As galaxy mergers can trigger star formation, we find that galaxies hosting low-mass black hole mergers tend to show a slight increase in star formation rates compared to a mass-matched sample. However, high-mass merger hosts have typical star formation rates, due to a combination of low gas fractions and powerful active galactic nucleus feedback. Although minor black hole mergers do not correlate with disturbed morphologies, major mergers (especially at high-masses) tend to show morphological evidence of recent galaxy mergers which survive for ∼500 Myr. This is on the same scale as the infall/hardening time of merging black holes, suggesting that electromagnetic follow-ups to gravitational wave signals may not be able to observe this correlation. We further find that incorporating a realistic time-scale delay for the black hole mergers could shift the merger distribution towards higher masses, decreasing the rate of LISA detections while increasing the rate of PTA detections.

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.

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