# Search for intermediate mass black hole binaries in the first observing run of Advanced LIGO

## TL;DR

This study conducted an all-sky search for gravitational waves from intermediate mass black hole binaries during LIGO's first observing run, setting new upper limits on merger rates due to no detections.

## Contribution

It applied two independent search techniques to constrain the rate of IMBHB mergers, significantly improving previous upper limits.

## Key findings

- No gravitational waves from IMBHBs were detected.
- The merger rate for 100 solar mass black holes is constrained to less than 0.93 Gpc^{-3} yr^{-1}.
- The upper limit improved by nearly two orders of magnitude.

## Abstract

During their first observational run, the two Advanced LIGO detectors attained an unprecedented sensitivity, resulting in the first direct detections of gravitational-wave signals and GW151226, produced by stellar-mass binary black hole systems. This paper reports on an all-sky search for gravitational waves (GWs) from merging intermediate mass black hole binaries (IMBHBs). The combined results from two independent search techniques were used in this study: the first employs a matched-filter algorithm that uses a bank of filters covering the GW signal parameter space, while the second is a generic search for GW transients (bursts). No GWs from IMBHBs were detected, therefore, we constrain the rate of several classes of IMBHB mergers. The most stringent limit is obtained for black holes of individual mass $100\,M_\odot$, with spins aligned with the binary orbital angular momentum. For such systems, the merger rate is constrained to be less than $0.93~\mathrm{Gpc^{-3}\,yr}^{-1}$ in comoving units at the $90\%$ confidence level, an improvement of nearly 2 orders of magnitude over previous upper limits.