Properties of the Binary Black Hole Merger GW150914

Abstract

On September 14, 2015, the Laser Interferometer Gravitational-Wave Observatory (LIGO) detected a gravitational-wave transient (GW150914); we characterize the properties of the source and its parameters. The data around the time of the event were analyzed coherently across the LIGO network using a suite of accurate waveform models that describe gravitational waves from a compact binary system in general relativity. GW150914 was produced by a nearly equal mass binary black hole of masses 36 þ5 −4 M ⊙ and 29 þ4 −4 M ⊙ ; for each parameter we report the median value and the range of the 90% credible interval. The dimensionless spin magnitude of the more massive black hole is bound to be < 0.7 (at 90% probability). The luminosity distance to the source is 410 −0.07 . This black hole is significantly more massive than any other inferred from electromagnetic observations in the stellar-mass regime.

GW150914: Implications for the Stochastic Gravitational-Wave Background from Binary Black Holes

“…The observed signal is consistent with a binary black hole waveform with component masses of m 1 ¼ 36 þ5 −4 M ⊙ and m 2 ¼ 29 þ4 −4 M ⊙ , as measured in the source frame, and coalescing at a luminosity distance of 410 þ160 −180 Mpc, corresponding to a redshift of z ¼ 0.09 þ0.03 −0.04 [4,5]. For every event like GW150914 observed by advanced gravitational-wave detectors, there are many more too distant to be resolved.…”

“…(vi) LowMass is the same as the Fiducial model except we add a second class of lower-mass binary black hole sources corresponding to a smaller range for individual detections during O1. As an example, we assume a chirp mass of half the mass of GW150914, M c ¼ 15M ⊙ and a local merger rate of 61 Gpc −3 yr −1 [5,16], corresponding to the second most significant event (LVT151012) identified in [4,39] with insufficient significance to decisively claim a detection. Here, we assume that the metallicity threshold is Z c ¼ Z ⊙ .…”

“…Inference on GW150914 [5], along with expectations that gravitational-wave emission is efficient in circularizing the orbit [15], allows us to restrict our models for dE GW =df s to circular orbits. Measurements do not constrain the component spins in the orbital plane [5]; therefore, we restrict our model to spins (anti-)aligned with the orbital angular momentum, and use the functional form of dE GW =df s derived in [20].…”

“…Inference on GW150914 [5], along with expectations that gravitational-wave emission is efficient in circularizing the orbit [15], allows us to restrict our models for dE GW =df s to circular orbits. Measurements do not constrain the component spins in the orbital plane [5]; therefore, we restrict our model to spins (anti-)aligned with the orbital angular momentum, and use the functional form of dE GW =df s derived in [20]. In addition to the component masses, this model depends on the effective spin parameter along the direction of the orbital angular momentum χ eff , which takes values between −1 (in which both black holes have maximal spins antialigned with respect to the orbital angular momentum) and þ1 (assuming maximally aligned spins) [5].…”

LIGO and the opening of a unique observational window on the universe

“…Shaded areas show 90% credible regions for two independent waveform reconstructions. One (dark gray) models the signal using binary black hole template waveforms (35). The other (light gray) does not use an astrophysical model, but instead calculates the strain signal as a linear combination of sine-Gaussian wavelets (33,41).…”