Gravitational Cherenkov Radiation from Extended Theories of Gravity

TL;DR

This paper investigates gravitational Cherenkov radiation in extended gravity theories, revealing additional massive modes beyond the standard graviton, and calculates their radiation emission rates in specific scenarios.

Contribution

It introduces a linearized analysis of higher order gravity theories with scalar invariants, identifying new massive spin-0 and spin-2 modes and their radiation characteristics.

Findings

Presence of massive spin-0 and spin-2 modes in extended gravity theories

Calculation of gravitational Cherenkov radiation emission rates for these modes

Identification of ghost modes among the massive spin-2 particles

Abstract

We linearize the field equations for higher order theories of gravity that contain scalar invariants other than the Ricci scalar. We find that besides a massless spin-2 field (the standard graviton), the theory contains also spin-0 and spin-2 massive modes with the latter being, in general, ghost modes. The rate at which such particles would emit gravitational Cherenkov radiation is calculated for some interesting physical cases.