Possible golden events for ringdown gravitational waves

TL;DR

This paper proposes two methods to test general relativity using gravitational wave data from binary black hole mergers, focusing on quasinormal modes and the forbidden parameter region, with promising event rate estimates for confirming Einstein's theory.

Contribution

It introduces two novel methods for testing general relativity through gravitational wave analysis of black hole quasinormal modes, considering realistic event rates.

Findings

Estimated detection rates of 500 events per year for binary black hole mergers.

Expected rates of over 30 events per year with high signal-to-noise ratios.

Potential to confirm or refute Einstein's theory in strong gravity regimes.

Abstract

There is a forbidden region in the parameter space of quasinormal modes of black holes in general relativity. Using both inspiral and ringdown phases of gravitational waves from binary black holes, we propose two methods to test general relativity. We also evaluate how our methods will work when we apply them to Pop III black-hole binaries with typical masses. Adopting the simple mean of the estimated range of the event rate, we have the expected rate of 500 ${\rm yr^{-1}}$. Then, the rates of events with signal-to-noise ratios greater than 20 and greater than 50 are 32 ${\rm yr^{-1}}$ and 2 ${\rm yr^{-1}}$, respectively. Therefore, there is a good chance to confirm (or refute) the Einstein theory in the strong gravity region by observing the expected quasinormal modes.