Multiband gravitational-wave parameter estimation: A study of future detectors

The first detection of a gravitational-wave signal of a coalescence of two black holes marked the beginning of the era of gravitational-wave astronomy, which opens exciting new possibilities in the fields of astronomy, astrophysics, and cosmology. The currently operating detectors of the LIGO and Virgo Collaborations are sensitive at relatively high frequencies, from 10 Hz up to about a kHz, and are able to detect gravitational waves emitted in a short time frame of less than a second (binary black holes) to minutes (binary neutron stars). Future missions like Laser Interferometer Space Antenna (LISA) will be sensitive in lower frequency ranges, which will make it possible to detect gravitational waves emitted long before these binaries merge. In this paper, we investigate the possibilities for parameter estimation using the Fisher-matrix formalism with combined information from present and future detectors in different frequency bands. The detectors we consider are the LIGO/Virgo detectors, the Einstein Telescope, LISA, and the first stage of the Deci-Hertz Interferometer Gravitational wave Observatory (B-DECIGO). The underlying models are constructed in time domain, which allows us to accurately model long-duration signal observations with multiband (or broadband) detector networks on parameter estimation. We assess the benefit of combining information from ground-based and space-borne detectors, and how choices of the orbit of B-DECIGO influence parameter estimates.