Binary black hole spectroscopy: a no-hair test of GW190814 and GW190412

TL;DR

This paper tests general relativity using gravitational wave data from high-mass-ratio black hole mergers GW190412 and GW190814, focusing on gravitational-wave harmonics beyond the dominant mode to search for deviations.

Contribution

It introduces a novel method to test GR by analyzing sub-dominant harmonics in gravitational wave signals from high-mass-ratio mergers, providing new constraints on deviations.

Findings

Results are consistent with GR.

Chirp mass of the (3, 3) mode within 0-5% of the dominant mode.

Constraints on deviations are tighter when only mass parameters are varied.

Abstract

Gravitational waves provide a window to probe general relativity (GR) under extreme conditions. The recent observations of GW190412 and GW190814 are unique high-mass-ratio mergers that enable the observation of gravitational-wave harmonics beyond the dominant $(\ell, m) = (2, 2)$ mode. Using these events, we search for physics beyond GR by allowing the source parameters measured from the sub-dominant harmonics to deviate from that of the dominant mode. All results are consistent with GR. We constrain the chirp mass as measured by the $(\ell, m) = (3, 3)$ mode to be within $0_{-3}^{+5}\%$ of the dominant mode when we allow both the masses and spins of the sub-dominant modes to deviate. If we allow only the mass parameters to deviate, we constrain the chirp mass of the $(3, 3)$ mode to be within $\pm1\%$ of the expected value from GR.