We report the observation of a gravitational-wave signal produced by the coalescence of two stellar-mass black holes. The signal, GW151226, was observed by the twin detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) on December 26, 2015 at 03:38:53 UTC. The signal was initially identified within 70 s by an online matched-filter search targeting binary coalescences. Subsequent off-line analyses recovered GW151226 with a network signal-to-noise ratio of 13 and a significance greater than 5σ. The signal persisted in the LIGO frequency band for approximately 1 s, increasing in frequency and amplitude over about 55 cycles from 35 to 450 Hz, and reached a peak gravitational strain of 3.4-0.9+0.7×10-22. The inferred source-frame initial black hole masses are 14.2-3.7+8.3M and 7.5-2.3+2.3M, and the final black hole mass is 20.8-1.7+6.1M. We find that at least one of the component black holes has spin greater than 0.2. This source is located at a luminosity distance of 440-190+180 Mpc corresponding to a redshift of 0.09-0.04+0.03. All uncertainties define a 90% credible interval. This second gravitational-wave observation provides improved constraints on stellar populations and on deviations from general relativity.
Publication Source (Journal or Book title)
Physical Review Letters
Abbott, B., Abbott, R., Abbott, T., Abernathy, M., Acernese, F., Ackley, K., Adams, C., Adams, T., Addesso, P., Adhikari, R., Adya, V., Affeldt, C., Agathos, M., Agatsuma, K., Aggarwal, N., Aguiar, O., Aiello, L., Ain, A., Ajith, P., Allen, B., Allocca, A., Altin, P., Anderson, S., Anderson, W., Arai, K., Araya, M., Arceneaux, C., Areeda, J., Arnaud, N., Arun, K., Ascenzi, S., Ashton, G., & Ast, M. (2016). GW151226: Observation of Gravitational Waves from a 22-Solar-Mass Binary Black Hole Coalescence. Physical Review Letters, 116 (24) https://doi.org/10.1103/PhysRevLett.116.241103