Tests of general relativity using multiband observations of intermediate mass binary black hole mergers. (arXiv:2006.12137v2 [gr-qc] UPDATED)
<a href="http://arxiv.org/find/gr-qc/1/au:+Datta_S/0/1/0/all/0/1">Sayantani Datta</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Gupta_A/0/1/0/all/0/1">Anuradha Gupta</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Kastha_S/0/1/0/all/0/1">Shilpa Kastha</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Arun_K/0/1/0/all/0/1">K. G. Arun</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Sathyaprakash_B/0/1/0/all/0/1">B. S. Sathyaprakash</a>
Observation of gravitational waves (GWs) in two different frequency bands is
referred to as multiband GW astronomy. With the planned Laser Interferometric
Space Antenna (LISA) operating in the $10^{-4}-0.1$ Hz range, and third
generation (3G) ground-based detectors such as the Cosmic Explorer (CE) and
Einstein Telescope (ET), operating in the $1$-$10^4$ Hz range, multiband GW
astronomy could be a reality in about a decade. In this paper we present the
potential of multiband observations of intermediate mass binary black holes
(IMBBHs) of component masses ${sim}10^2$-$10^3,M_{odot}$ to test general
relativity (GR). We show that mutiband observations of IMBBHs would permit
multiparameter tests of GR-tests where more than one post-Newtonian (PN)
coefficient is simultaneously measured yielding more rigorous constraints on
possible modifications to GR. We also find that the improvement due to
multibanding can often be much larger than the best of the bounds from either
of the two observatories. The origin of this result, as we shall demonstrate,
can be traced to the lifting of degeneracies among the various parameters when
the information from LISA and 3G are taken together. We obtain the best
multiband bounds for an IMBBH with a total redshifted mass of $200,M_{odot}$
and a mass ratio of 2. For single-parameter tests, this system at 1 Gpc would
allow us to constrain the deviations on all the PN coefficients to below $10%$
and derive simultaneous bounds on the first seven PN coefficients to below
$50%$ (with low spins).
Observation of gravitational waves (GWs) in two different frequency bands is
referred to as multiband GW astronomy. With the planned Laser Interferometric
Space Antenna (LISA) operating in the $10^{-4}-0.1$ Hz range, and third
generation (3G) ground-based detectors such as the Cosmic Explorer (CE) and
Einstein Telescope (ET), operating in the $1$-$10^4$ Hz range, multiband GW
astronomy could be a reality in about a decade. In this paper we present the
potential of multiband observations of intermediate mass binary black holes
(IMBBHs) of component masses ${sim}10^2$-$10^3,M_{odot}$ to test general
relativity (GR). We show that mutiband observations of IMBBHs would permit
multiparameter tests of GR-tests where more than one post-Newtonian (PN)
coefficient is simultaneously measured yielding more rigorous constraints on
possible modifications to GR. We also find that the improvement due to
multibanding can often be much larger than the best of the bounds from either
of the two observatories. The origin of this result, as we shall demonstrate,
can be traced to the lifting of degeneracies among the various parameters when
the information from LISA and 3G are taken together. We obtain the best
multiband bounds for an IMBBH with a total redshifted mass of $200,M_{odot}$
and a mass ratio of 2. For single-parameter tests, this system at 1 Gpc would
allow us to constrain the deviations on all the PN coefficients to below $10%$
and derive simultaneous bounds on the first seven PN coefficients to below
$50%$ (with low spins).
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