2021/10/29 by Islam, Tousif
#FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc)
paper · doi:10.48550/arxiv.2111.00111
As one of the consequences of the black-hole "no-hair" theorem in general relativity (GR), the multipolar structure of the radiation (i.e. different spherical harmonic modes) from a merging quasi-circular binary black hole (BBH) is fully determined by the intrinsic parameters (i.e. the masses and spins of the companion black holes). In Refs. [1,2], we have formulated an efficient test named `higher-modes consistency test' to check for the consistency of the observed gravitational-wave (GW) signal with the expected multipolar structure of radiation from BBHs in GR. Detection of the high-mass-ratio merger of GW190814 enables the observation of spherical harmonic modes beyond the dominant (ℓ, m) = (2,±2) mode; thereby providing a unique opportunity to perform the `higher-modes consistency test'. Using different state-of-art waveform models (IMRPhenomXPHM, IMRPhenomXHM, IMRPhenomHM and SEONNRv4HMROM), we show that GW190814 strongly favors the "no-hair" hypothesis in GR over a hypothesis that assumes generic deviation from the multipolar structure of the radiation by a Bayes factor of \rm logeB∼8. We further investigate any potential systematic errors arising as a result of different waveform modeling choices as well as due to neglecting many higher order modes. We find that, if the waveform model includes only (ℓ, m) = (3,±3) mode in its higher harmonics, the same event may reject the `no-hair' hypothesis in GR when the detector sensitivity improves by a factor of 12.5. Our analysis, therefore, provides motivation to include as many higher order modes as possible in future waveform models.