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Symmetry ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 118
Author(s):  
Yu-Xiao Liu ◽  
Yu-Han Ma ◽  
Yong-Qiang Wang ◽  
Shao-Wen Wei ◽  
Chang-Pu Sun

It has been shown that the nonthermal spectrum of Hawking radiation will lead to information-carrying correlations between emitted particles in the radiation. The mutual information carried by such correlations can not be locally observed and hence is dark. With dark information, the black hole information is conserved. In this paper, we look for the spherically symmetric black hole solution in a λφ fluid model and investigate the radiation spectrum and dark information of the black hole. The spacetime structure of this black hole is similar to that of the Schwarzschild one, while its horizon radius is decreased by the λφ fluid. By using the statistical mechanical method, the nonthermal radiation spectrum is calculated. This radiation spectrum is very different from the Schwarzschild case at its last stage because of the effect of the λφ fluid. The λφ fluid reduces the lifetime of the black hole, but increases the dark information of the Hawking radiation.


Author(s):  
R P Singh ◽  
B K Singh ◽  
B R K Gupta ◽  
S Sachan

The Bardeen black hole solution is the first spherically symmetric regular black hole based on the Sakharov and Gliner proposal which is the modification of the Schwarzschild black hole. We present the Bardeen black hole solution in presence of the dRGT massive gravity, which is regular everywhere in the presence of a nonlinear source. The obtained solution interpolates with the Bardeen black hole in the absence of massive gravity parameter and the Schwarzschild black hole in the limit of magnetic charge g=0. We investigate the thermodynamical quantities viz. mass (M), temperature (T), entropy (S) and free energy (F) in terms of horizon radius for both canonical and grand canonical ensembles. We check the local and global stability of the obtained solution by studying the heat capacity and free energy. The heat capacity flips the sign at r = r<sub>c</sub>. The black hole is thermodynamically stable with positive heat capacity C>0 for i.e., globally preferred with negative free energy F < 0. In addition, we also study the phase structure of the obtained solution in both ensembles.


2021 ◽  
pp. 2150137
Author(s):  
Shahid Chaudhary ◽  
Abdul Jawad ◽  
Kimet Jusufi ◽  
Muhammad Yasir

This paper explores the influence of special type of higher order generalized uncertainty principle on the thermodynamics of five-dimensional black hole in Einstein–Gauss–Bonnet gravity coupled to nonlinear electrodynamics. We examine the corrected thermodynamical properties of the black hole with some interesting limiting cases [Formula: see text] and [Formula: see text] and compared our results with usual thermodynamical relations. We observe that the influence of GUP correction stabilizes the BH and BH solution remains physical throughout the region of horizon radius. In this framework, we also uncover the relationship of shadow radius and quasinormal modes of the mentioned black hole. We conclude that shadow radius of our considered black hole is a perfect circle and it decreases with increasing values of charge and Gauss–Bonnet parameter. We also verify the inverse relation between the quasinormal modes frequencies and shadow radius, i.e. quasinormal modes should increase with increasing values of Gauss–Bonnet parameter and electric charge.


2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Alex Davey ◽  
Oscar J. C. Dias ◽  
Paul Rodgers

Abstract We find the phase diagram of solutions of the charged black hole bomb system. In particular, we find the static hairy black holes of Einstein-Maxwell-Scalar theory confined in a Minkowski box. We impose boundary conditions such that the scalar field vanishes at and outside a cavity of constant radius. These hairy black holes are asymptotically flat with a scalar condensate floating above the horizon. We identify four critical scalar charges which mark significant changes in the qualitative features of the phase diagram. When they coexist, hairy black holes always have higher entropy than the Reissner-Nordström black hole with the same quasilocal mass and charge. So hairy black holes are natural candidates for the endpoint of the superradiant/near-horizon instabilities of the black hole bomb system. We also relate hairy black holes to the boson stars of the theory. When it has a zero horizon radius limit, the hairy black hole family terminates on the boson star family. Finally, we find the Israel surface tensor of the box required to confine the scalar condensate and that it can obey suitable energy conditions.


2021 ◽  
Vol 81 (4) ◽  
Author(s):  
Chen-Hao Wu ◽  
Ya-Peng Hu ◽  
Hao Xu

AbstractEinstein–Gauss–Bonnet theory is a string-generated gravity theory when approaching the low energy limit. By introducing the higher order curvature terms, this theory is supposed to help to solve the black hole singularity problem. In this work, we investigate the evaporation of the static spherically symmetric neutral AdS black holes in Einstein–Gauss–Bonnet gravity in various spacetime dimensions with both positive and negative coupling constant $$\alpha $$ α . By summarizing the asymptotic behavior of the evaporation process, we find the lifetime of the black holes is dimensional dependent. For $$\alpha >0$$ α > 0 , in $$D\geqslant 6$$ D ⩾ 6 cases, the black holes will be completely evaporated in a finite time, which resembles the Schwarzschild-AdS case in Einstein gravity. While in $$D=4,5$$ D = 4 , 5 cases, the black hole lifetime is always infinite, which means the black hole becomes a remnant in the late time. Remarkably, the cases of $$\alpha >0, D=4,5$$ α > 0 , D = 4 , 5 will solve the terminal temperature divergent problem of the Schwarzschild-AdS case. For $$\alpha <0$$ α < 0 , in all dimensions, the black hole will always spend a finite time to a minimal mass corresponding to the smallest horizon radius $$r_{min}=\sqrt{2|\alpha |}$$ r min = 2 | α | which coincide with an additional singularity. This implies that there may exist constraint conditions to the choice of coupling constant.


2021 ◽  
pp. 2150048
Author(s):  
Yuan Chen ◽  
He-Xu Zhang ◽  
Tian-Chi Ma ◽  
Jian-Bo Deng

In this paper, we discussed optical properties of the nonlinear magnetic charged black hole surrounded by quintessence with a nonzero cosmological constant [Formula: see text]. Setting the state parameter [Formula: see text], we studied the horizons, the photon region and the shadow of this black hole. It turned out that for a fixed quintessential parameter [Formula: see text], in a certain range, with the increase of the rotation parameter [Formula: see text] and magnetic charge [Formula: see text], the inner horizon radius increases while the outer horizon radius decreases. The cosmological horizon [Formula: see text] decreases when [Formula: see text] or [Formula: see text] increases and it increases slightly when [Formula: see text] and [Formula: see text] increase. The shapes of photon region were then studied and depicted through graphical illustrations. Finally, we discussed the effects of the quintessential parameter [Formula: see text] and the cosmological constant [Formula: see text] on the shadow of this black hole with a fixed observer position in the domain of outer communication.


2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Yun-Zhi Du ◽  
Hui-Hua Zhao ◽  
Li-Chun Zhang

The phase transition of the Einstein-Gauss-Bonnet AdS black hole has the similar property with the van der Waals thermodynamic system. However, it is determined by the Gauss-Bonnet coefficient α , not only the horizon radius. Furthermore, the phase transition is not the pure one between a big black hole and a small black hole. With this issue, we introduce a new order parameter to investigate the critical phenomenon and to give the microstructure explanation of the Einstein-Gauss-Bonnet AdS black hole phase transition. And the critical exponents are also obtained. At the critical point of the Einstein-Gauss-Bonnet AdS black hole, we reveal the microstructure of the black hole by investigating the thermodynamic geometry. These results perhaps provide some certain help to deeply explore the black hole microscopic structure and to build the quantum gravity.


Author(s):  
Aalok Misra ◽  
Charles Gale

Abstract Obtaining a lattice-consistent result for the temperature dependence of the QCD conformal anomaly from a top-down M-theory dual (valid) for all temperatures – both, $$T<T_c$$T<Tc and $$T>T_c$$T>Tc – of thermal QCD at intermediate gauge coupling, has been missing in the literature. We fill this gap by addressing this issue from the M-theory uplift of the SYZ type IIA mirror at intermediate gauge/string coupling [both obtained in Dhuria et al. (JHEP 1311:001, 2013)] of the UV-complete type IIB holographic dual of large-N thermal QCD of Mia et al. (Nucl Phys B 839:187, 2010), and comparing with the very recent lattice results of Bazavov et al. (Phys Rev D 97(1):014510, 2018). Estimates of the $$\mathcal{O}(R^4)$$O(R4) higher derivative corrections in the $$D=11$$D=11 supergravity action relevant to considering the aforementioned M theory uplift in the intermediate ’t Hooft coupling (in addition to gauge coupling) limit, are also presented. We also show that after a tuning of the (small) Ouyang embedding parameter and radius of a blown-up $$S^2$$S2 when expressed in terms of the horizon radius, a QCD deconfinement temperature $$T_c=150$$Tc=150 MeV from a Hawking–Page phase transition at vanishing baryon chemical potential consistent with lattice QCD in the heavy-quark limit, can be obtained.


2020 ◽  
Vol 35 (18) ◽  
pp. 2050080
Author(s):  
Nadeem-ul-islam ◽  
Prince A. Ganai

In this paper, we explore the effect of quantum fluctuations on the thermodynamic potentials, characterizing the (2[Formula: see text]+[Formula: see text]1)-dimensional AdS black hole with the negative cosmological constant in massive gravity. The (2[Formula: see text]+[Formula: see text]1)-dimensional black hole solution was discovered by three pioneer scientists, Banados, Teitelboim, and Zanelli in 1992 and hence is named as BTZ black hole.[Formula: see text] First, we present the brief idea of the BTZ black hole solution in massive gravity and then estimate the leading order corrections to thermodynamic potentials characterizing BTZ black hole in massive gravity. The qualitative analysis is done by plotting the corrected thermodynamic potentials against the event horizon radius for distinct values of the correction parameter. The correction parameter [Formula: see text] measures the strength of quantum fluctuations.


Author(s):  
Mohammed B. Al-Fadhli

The necessity of the dark energy and dark matter in the present universe could be a consequence of the antimatter elimination assumption in the early universe. In this research, I derive a new model to obtain the cosmic horizon radius and the potential cosmic topology utilising a new construal of space geometry inspired by large-angle correlations of the cosmic microwave background (CMB). A version of the Big Bounce theory is utilised to avoid the Big Bang singularity and inflationary constraints, and to tune the initial conditions of the curvature density. The mathematical derivation of a positively curved universe governed by only gravity revealed two cosmic horizon solutions. Although the positive horizon is conventionally associated with the evolution of the matter universe, the negative horizon solution could imply additional evolution in the opposite direction. This possibly suggests that the matter and antimatter could be evolving in opposite directions as distinct sides of the universe, as in the visualised Sloan Digital Sky Survey. The cosmic horizon radius is found to be accountable for the universal space curvature. By implementing this model, we find a decelerated stage of expansion during the first 10 Gyr, which is followed by a second stage of an accelerated expansion; potentially matching the tension in Hubble parameter measurements. In addition, the model predicts a final time-reversal stage of spatial contraction leading to the Big Crunch of a cyclic universe. The predicted density is 1.14. Other predictions are (1) a calculable flow rate of the matter side towards the antimatter side at the accelerated stage; conceivably explaining the dark flow observation, (2) a time-dependent spacetime curvature over horizon evolution, which could influence the galactic rotational speed; possibly explaining the high speed of stars, and (3) evolvable spacetime internal voids at the accelerated stage, which could contribute in continuously increasing the matter and antimatter densities elsewhere in both sides respectively. These findings may indicate the existence of the antimatter as a distinct side, which influences the evolution of the universe instead of the dark energy or dark matter.


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