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We report a new binary black hole merger in the publicly available LIGO First Observing Run (O1) data release. The event has an inverse false alarm rate of one per six years in the detector-frame chirp-mass range $\mathcal{M}^{\rm det} \in [20,40]M_\odot$ in a new independent analysis pipeline that we developed. Our best estimate of the probability that the event is of astrophysical origin is $P_{\rm astro} \sim 0.71\, .$ The estimated physical parameters of the event indicate that it is the merger of two massive black holes, $\mathcal{M}^{\rm det} = 31^{+2}_{-3}\,M_\odot$ with an effective spin parameter, $\chi_{\rm eff} = 0.81^{+0.15}_{-0.21}$, making this the most highly spinning merger reported to date. It is also among the two highest redshift mergers observed so far. The high aligned spin of the merger supports the hypothesis that merging binary black holes can be created by binary stellar evolution.

We report a new BBH merger in the public data from the First Observing Run of advanced LIGO. The candidate has a detector-frame chirp mass Mdet = 31+2−3 M, and has a FAR of 1 per 52 O1 in the bank with chirpmasses Mdet ∈ 20 − 40 M. It is among the highest redshift events discovered thus far. The inferred value for the effective spin parameter χeff ‘ 0.8 is the highest among the BBHs detected to date, and points to the system consisting of two rapidly spinning black holes, with spins aligned with the orbital plane. Future detections of BBH mergers similar to our candidate can confirm the existence of a population of fast-spinning and aligned mergers; correlations between the spins, mass-ratios, and source redshifts can shed light on the astrophysical origin of these mergers. Such a population is unlikely in dynamical formation scenarios, but is characteristic of stellar binary evolution.