Scope out multiband gravitational-wave observations of GW190521-like binary black holes with space gravitational wave antenna B-DECIGO

TL;DR

This paper investigates the potential of multiband gravitational wave observations across space- and ground-based detectors to analyze GW190521-like black hole mergers, enhancing parameter estimation and tests of general relativity.

Contribution

It demonstrates the scientific benefits of combined multiband observations with LISA, B-DECIGO, and ground-based detectors for GW190521-like binaries, including improved parameter estimation and strong-field tests.

Findings

Triple-band observation can estimate black hole parameters with 1-10% accuracy.

Multiband signals can achieve SNR > 100 for eccentric binaries over five years.

Multiband observations enable precise tests of general relativity.

Abstract

The gravitational wave event, GW190521 is the most massive binary black hole merger observed by ground-based gravitational wave observatories LIGO/Virgo to date. While the observed gravitational-wave signal is mainly in the merger and ringdown phases, the inspiral gravitational-wave signal of GW190521-like binary will be more visible by space-based detectors in the low-frequency band. In addition, the ringdown gravitational-wave signal will be more loud with the next generation (3G) of ground-based detectors in the high-frequency band, displaying a great potential of the multiband gravitational wave observations. In this paper, we explore the scientific potential of multiband observations of GW190521-like binaries with milli-Hz gravitational wave observatory: LISA, deci-Hz observatory: B-DECIGO, and (next generation of) hecto-Hz observatories: aLIGO and ET. In the case of quasicircular evolution, the triple-band observation by LISA, B-DECIGO and ET will provide parameter estimation errors of the masses and spin amplitudes of component black holes at the level of order 1% -- 10%. This would allow consistency tests of general relativity in the strong-field at an unparalleled precision, particularly with the "B-DECIGO + ET" observation. In the case of eccentric evolution, the multiband signal-to-noise ratio by "B-DECIGO + ET" observation would be larger than 100 for a five year observation prior to coalescence, even with high final eccentricities.