scholarly journals Improved Reissner–Nordström–(A)dS black hole in asymptotic safety

2016 ◽  
Vol 31 (26) ◽  
pp. 1650141 ◽  
Author(s):  
Cristopher González ◽  
Benjamin Koch
Keyword(s):  
Black Hole ◽  
Einstein Gravity ◽  
Cosmic Censorship ◽  
Black Hole Mass ◽  
Crucial Point ◽  
Group Approach ◽  
Functional Renormalization Group ◽  
Charged Black Holes ◽  
Renormalization Group Approach ◽  
Cosmic Censorship Hypothesis

This paper studies the quantum modifications of the Reissner–Nordström–(A)dS black hole within Quantum Einstein Gravity, coupled to an electromagnetic sector. Quantum effects are introduced on the level of the improvements of the classical solution, where the originally constant couplings ([Formula: see text], [Formula: see text] and [Formula: see text]) are promoted to scale dependent quantities ([Formula: see text], [Formula: see text] and [Formula: see text]). Those running couplings are calculated in the functional renormalization group approach. A crucial point of this so-called “improving solutions” procedure is the scale setting where the arbitrary scale [Formula: see text] acquires physical meaning due to a relation to the coordinate scale [Formula: see text]. It is proposed to use such scale settings which are stable after iterative improvements. Using this method one finds that for those improved solutions, there is no stable remnant and due to the appearance of a new internal horizon, there is also no necessity to impose a minimal black hole mass for charged black holes, in order to avoid the cosmic censorship hypothesis.

scholarly journals Black hole evaporation in Hořava–Lifshitz gravity

2020 ◽  
Vol 80 (7) ◽  
Author(s):  
Hao Xu ◽  
Yen Chin Ong
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Lorentz Invariance ◽  
Detailed Balance ◽  
Einstein Gravity ◽  
Zero Temperature ◽  
Black Hole Mass ◽  
Black Hole Evaporation ◽  
Higher Derivative ◽  
Temperature State

Abstract Hořava–Lifshitz (HL) gravity was formulated in hope of solving the non-renormalization problem in Einstein gravity and the ghost problem in higher derivative gravity theories by violating Lorentz invariance. In this work we consider the spherically symmetric neutral AdS black hole evaporation process in HL gravity in various spacetime dimensions d, and with detailed balance violation parameter $$0\leqslant \epsilon ^2\leqslant 1$$0⩽ϵ2⩽1. We find that the lifetime of the black holes under Hawking evaporation is dimensional dependent, with $$d=4,5$$d=4,5 behave differently from $$d\geqslant 6$$d⩾6. For the case of $$\epsilon =0$$ϵ=0, in $$d=4,5$$d=4,5, the black hole admits zero temperature state, and the lifetime of the black hole is always infinite. This phenomenon obeys the third law of black hole thermodynamics, and implies that the black holes become an effective remnant towards the end of the evaporation. As $$d\geqslant 6$$d⩾6, however, the lifetime of black hole does not diverge with any initial black hole mass, and it is bounded by a time of the order of $$\ell ^{d-1}$$ℓd-1, similar to the case of Schwarzschild-AdS in Einstein gravity (which corresponds to $$\epsilon ^2=1$$ϵ2=1), though for the latter this holds for all $$d\geqslant 4$$d⩾4. The case of $$0<\epsilon ^2<1$$0<ϵ2<1 is also qualitatively similar with $$\epsilon =0$$ϵ=0.

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