Hunting for intermediate-mass black holes with LISA binary radial velocity measurements
ORAL
Abstract
Despite their potential role as massive seeds for quasars, in dwarf galaxy feedback, and in tidal disruption events, the observational evidence for intermediate-mass black holes (IMBHs) is scarce. LISA may observe stellar-mass black hole binaries orbiting Galactic IMBHs, and reveal the presence of the IMBH by measuring the Doppler shift in the gravitational waveform induced by the binary's radial velocity. We estimate the number of detectable Doppler shift events and we find that it decreases with the IMBH mass. A few Galactic globular clusters (including M22 and ω Centauri) may produce at least one event detectable by LISA if they harbor an IMBH at their center. We also estimate the number of expected Doppler shift events for IMBHs wandering in the Milky Way as a result of the disruption of their parent clusters. If there is at least one binary black hole orbiting around each wandering IMBH (assuming each destroyed GC left behind an IMBH), LISA may detect tens of Doppler shift events from IMBHs wandering in our Galaxy, and produce a map of this elusive population.
*V.S., T.H. K.W.K.W. and E.B. were supported by NSF Grants No. PHY-1912550 and AST-2006538, NASA ATP Grants No. 17-ATP17-0225 and 19-ATP19-0051, NSF-XSEDE Grant No. PHY-090003, and NSF Grant PHY-20043. V.S., T.H., G.F. and E.B. are in part supported by NASA Grant 20-LPS20-0011 (Grant No. 80NSSC21K1722). G.F. acknowledges support from NSF Grant AST-1716762 at Northwestern University. K.W.K.W. is supported by the Simons Foundation. This research project was conducted using computational resources at the Maryland Advanced Research Computing Center (MARCC). The authors acknowledge the Texas Advanced Computing Center (TACC; http://www.tacc.utexas.edu) at The University of Texas at Austin for providing HPC resources that have contributed to these research results.
