Gravity in mimetic scalartensor theories after GW170817
Abstract
We derive the most general mimetic scalartensor theory assuming a healthy "seed" action and accounting for the constraints on the speed of gravitationalwave propagation arising from the GW170817 event. By analysing linear perturbations around a flat FLRW background in this model, we obtain a suitable form of the Poisson equation, which allows us to calculate the effective gravitational constant felt by "ordinary" matter. By restricting to a minimally coupled model, such an effective gravitational constant is equivalent to that obtained within General Relativity, with cold dark matter plus a perfect fluid dark energy component, with vanishing sound speed. Assuming, further, a ΛCDM background, the effective gravitational constant cannot be distinguished from that of the standard ΛCDM model, at linear order. For the full nonminimally coupled mimetic gravity model we obtain a nonvanishing gravitational slip and an effective gravitational constant which always differs from that of standard ΛCDM .
 Publication:

Journal of Cosmology and Astroparticle Physics
 Pub Date:
 January 2019
 DOI:
 10.1088/14757516/2019/01/056
 arXiv:
 arXiv:1809.03496
 Bibcode:
 2019JCAP...01..056G
 Keywords:

 General Relativity and Quantum Cosmology;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 20 pages, 0 figures