On the detectability of massive black hole merger events by Laser Interferometry Space Antenna

ABSTRACT The launch of space-based gravitational-wave (GW) detectors (e.g. Laser Interferometry Space Antenna; LISA) and current upcoming Pulsar Timing Arrays will extend the GW window to low frequencies, opening new investigations into dynamical processes involving massive black hole binaries (MBHBs) their mergers across cosmic time. MBHBs are expected be among primary sources for low-frequency (10−4–10−1 Hz) probed by LISA. It is important investigate supermassive BH merger rates associated signals, determine how potential LISA events affected physics included in models. To study this, we post-process large population Illustris simulation account friction time delays with infall/inspiral. We show that binary evolution have decrease rates, $M_{\rm {BH}}\ \gt\ 10^6\ \mathrm{M}_\odot$ (the lowest mass Illustris) decreasing from ∼3 ∼0.1 yr−1, shifting peak z ∼2 ∼1.25. During this time, estimate accretion grows total merging as much 7x original mass. Importantly, however, friction-associated (which shift toward lower redshift higher masses) lead a stronger signal/strain emitted GWs band, increasing mean frequency 10−3.1 10−3.4–10−4.0 Hz, strain 10−17.2 10−16.3–10−15.3. Finally, after including delay MBH growth, still tend lie on typical MBH–M* relation, but an increased likelihood undermassive BH.