Fluid nature constrains Horndeski gravity

被引：0
作者：
Marcello Miranda
Daniele Vernieri
Salvatore Capozziello
Valerio Faraoni
机构：
[1] Scuola Superiore Meridionale,Dipartimento di Fisica “E. Pancini”
[2] Istituto Nazionale di Fisica Nucleare,Department of Physics and Astronomy
[3] Sez. di Napoli,undefined
[4] Compl. Univ. Monte S. Angelo,undefined
[5] Edificio G,undefined
[6] Università di Napoli “Federico II”,undefined
[7] Compl. Univ. Monte S. Angelo,undefined
[8] Edificio G,undefined
[9] Bishop’s University,undefined
来源：
General Relativity and Gravitation | 2023年 / 55卷
关键词：
Modified gravity; Cosmology; Effective fluids;
D O I：
暂无
中图分类号：
学科分类号：
摘要：
The elusive physical nature of Horndeski gravity is elucidated in a new approach depicting this class of theories as a dissipative effective fluid. Requiring the constitutive equations of the latter to be those of a Newtonian fluid restricts the theory to only two disconnected subclasses of “viable” Horndeski gravity. Therefore, a stress-energy tensor of the Horndeski effective fluid, linear in the first derivatives of the fluid’s 4-velocity, is a sufficient condition for gravitational waves to propagate at light speed. All other Horndeski theories correspond to exotic non-Newtonian effective fluids. The two linear Horndeski classes are studied in the framework of first-order thermodynamics of viscous fluids, which further constrains the functional form of the theory.
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