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arXiv · 2209.02727

Fluid nature constrains Horndeski gravity

Marcello Miranda·Daniele Vernieri·Salvatore Capozziello·Valerio Faraoni
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Abstract

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 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.

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Marcello Miranda, Daniele Vernieri, Salvatore Capozziello, Valerio Faraoni. 2022-09-06. Fluid nature constrains Horndeski gravity. https://doi.org/10.1007/s10714-023-03128-1

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