Item

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 $\ell = m = 2$ 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
$\ell = m = 3$ mode to be within $0_{-4}^{+6}\%$ 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
$\ell = m = 3$ mode to be within $\pm1\%$ of the expected value from GR.