Distinguishing general relativity from Chern-Simons gravity using gravitational wave polarizations

Abstract

Quasinormal modes (QNMs) uniquely characterize the final black hole. Until now, only the QNM frequency and damping time have been used to test general relativity. In this work, we show explicitly that another property of the QNMs - their polarization - can be a reliable tool for probing gravity. We provide a consistent test for general relativity by considering Chern-Simons gravity. Distinguishing Chern-Simons gravity from general relativity using only template matching is highly challenging. Thus, a parameter that can differentiate between Chern-Simons gravity and GR will be a suitable candidate for any modified theories of gravity. We discuss the implications of our result for the future gravitational wave detectors.