Gravitational-wave Detection and Parameter Estimation for Accreting Black-hole Binaries and Their Electromagnetic Counterpart

Abstract

We study the impact of gas accretion on the orbital evolution of black-hole binaries initially at large separation in the band of the planned Laser Interferometer Space Antenna (LISA). We focus on two sources: (i) stellar-origin black-hole binaries (SOBHBs) that can migrate from the LISA band to the band of ground-based gravitational-wave (GW) observatories within weeks/months; and (ii) intermediate-mass black-hole binaries (IMBHBs) in the LISA band only. Because of the large number of observable GW cycles, the phase evolution of these systems needs to be modeled to great accuracy to avoid biasing the estimation of the source parameters. Accretion affects the GW phase at negative (−4) post-Newtonian order, being thus dominant for binaries at large separations. Accretion at the Eddington or at super-Eddington rate will leave a detectable imprint on the dynamics of SOBHBs. For super-Eddington rates and a 10-years mission, a multiwavelength strategy with LISA and a groundbased interferometer can detect about 10 (a few) SOBHB events for which the accretion rate can be measured at 50% (10%) level. In all cases the sky position can be identified within much less than 0.4 deg 2 uncertainty. Likewise, accretion at 100% of the Eddington rate can be measured in IMBHBs up to redshift z ≈ 0.1, and the position of these sources can be identified within less than 0.01 deg 2 uncertainty. Altogether, a detection of SOBHBs or IMBHBs would allow for targeted searches of electromagnetic counterparts to black-hole mergers in gas-rich environments with future X-ray detectors (such as Athena) and/or radio observatories (such as SKA).

Science case for the Einstein telescope

“…The actual possibility of multi-band detections depends sensitively on a number of issues, in particular on the sensitivity curve assumed for LISA, particularly at high frequency, on the details of the data analysis in LISA, and on the mass distribution of the component BHs in a BH-BH binary. The recent analysis in [145] finds that LISA, in a 4 yr mission, will detect several tens of stellar-mass BH-BH binaries, consistently with the earlier estimates in [144,146]. 4 Figure 9.…”

“…Smaller estimates have been obtained in[147], using a pessimistic LISA sensitivity curve at high frequencies, rather than the official sensitivity curve of the LISA proposal used in[145]. This highlights the importance of the sensitivity curve at high frequencies, as well as of the other assumptions entering the estimates.…”

GW190521 Mass Gap Event and the Primordial Black Hole Scenario

“…The corrective factors account for the hardening of the binary at z < z cutoff [39,76] and the augmented energy loss through GW emission [77,78], both due to the mass accretion of each PBHs. An additional contribution comes from binaries formed in the late-time Universe, whose rate density is [6,9]…”

Archival searches for stellar-mass binary black holes in LISA data

“…In the same spirit, we have not included any ultralight boson clouds or other fields that might surround the companion black holes in the low-frequency phase of the evolution. This could alter the orbital evolution but would not be relevant at later stages [64,65].…”