LIGO Document P1900045-v16
- Gravitational wave astronomy has been firmly established with the direct detection of gravitational waves from the merger of ten stellar mass binary black holes and a neutron star binary. This paper reports on the all-sky search for gravitational waves from intermediate-mass black hole binaries (IMBHB) in the first and second observing runs of the Advanced LIGO and Virgo network. The search uses three independent algorithms: two based on matched filtering of the data with waveform templates of gravitational wave signals from compact binaries, and a third that is agnostic about the morphology of the incoming signal. No IMBHB events were detected by this search. Consequently, we place upper limits on the merger rate density for different IMBHB systems with total mass in the range of 120~\( {\rm M}_\odot \leq~M_{\rm tot} \leq~800~{\rm M}_\odot \) and mass ratio of \( 1 \leq q \leq10 \). The calculation of these upper limits is distinct from the IMBHB search of Ref.~\cite{Abbott:2017iws}.For the first time, our constraints are computed using the most realistic IMBHB waveforms obtained from numerical relativity, which include higher order modes. Our most stringent upper limit on the merger rate density is for IMBH systems with two \( 100~{\rm M}_\odot \) black holes and spins aligned with the orbital angular momentum. This upper limit on the merger rate density is \tcr{\( 0.20 ~{\rm Gpc}^{-3}{\rm yr}^{-1} \)} in comoving units at the 90\% confidence level, which is an improvement of a factor of \tcr{\( \sim 5 \)} over that reported after Advanced LIGO's first observing run ~\cite{Abbott:2017iws}.
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