On black hole temperature in Horndeski gravity

Hajian K., Liberati S., Sheikh-Jabbari M. M., Vahidinia M. H.

PHYSICS LETTERS B, vol.812, 2021 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 812
  • Publication Date: 2021
  • Doi Number: 10.1016/j.physletb.2020.136002
  • Journal Name: PHYSICS LETTERS B
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Aerospace Database, Chemical Abstracts Core, INSPEC, zbMATH, Directory of Open Access Journals
  • Keywords: Black hole thermodynamics, Horndeski gravity, Wald entropy, Hawking radiation, ENTROPY, TENSOR
  • Middle East Technical University Affiliated: Yes

Abstract

It has been observed that for black holes in certain family of Horndeski gravity theories Wald's entropy formula does not lead to the correct first law for black hole thermodynamics. For this family of Horndeski theories speeds of propagation of gravitons and photons are in general different and gravitons move on an effective metric different than the one seen by photons. We show that the temperature of the black hole should be modified from surface gravity over 2 pi to include effects of this effective metric. The modified temperature, with the entropy unambiguously computed by the solution phase space method, yields the correct first law. Our results have far reaching implications for the Hawking radiation and species problem, going beyond the Horndeski theories. (C) 2020 The Author(s). Published by Elsevier B.V.