Deflection of light by rotating regular black holes using the Gauss-Bonnet theorem

We describe the observation of GW170104, a gravitational-wave signal produced by the coalescence of a pair of stellar-mass black holes. The signal was measured on January 4, 2017 at 10:11:58.6 UTC by the twin advanced detectors of the Laser Interferometer Gravitational-Wave Observatory during their second observing run, with a network signal-to-noise ratio of 13 and a false alarm rate less than 1 in 70,000 years. The inferred component black hole masses are \(31.2^{+8.4}_{-6.0}\,M_\odot\) and \(19.4^{+5.3}_{-5.9}\,M_\odot\) (at the 90% credible level). The black hole spins are best constrained through measurement of the effective inspiral spin parameter, a mass-weighted combination of the spin components perpendicular to the orbital plane, \(\chi_\mathrm{eff} = -0.12^{+0.21}_{-0.30}.\) This result implies that spin configurations with both component spins positively aligned with the orbital angular momentum are disfavored. The source luminosity distance is \(880^{+450}_{-390}~\mathrm{Mpc}\) corresponding to a redshift of \(z = 0.18^{+0.08}_{-0.07}\). We constrain the magnitude of modifications to the gravitational-wave dispersion relation and perform null tests of general relativity. Assuming that gravitons are dispersed in vacuum like massive particles, we bound the graviton mass to \(m_g \le 7.7 \times 10^{-23}~\mathrm{eV}/c^2\). In all cases, we find that GW170104 is consistent with general relativity.

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 \(36^{+5}_{-4} M_\odot\) and \(29^{+4}_{-4} M_\odot\); 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 \(410^{+160}_{-180}\) Mpc, corresponding to a redshift \(0.09^{+0.03}_{-0.04}\) assuming standard cosmology. The source location is constrained to an annulus section of \(610\) deg\(^2\), primarily in the southern hemisphere. The binary merges into a black hole of \(62^{+4}_{-4} M_\odot\) and spin \(0.67^{+0.05}_{-0.07}\). This black hole is significantly more massive than any other inferred from electromagnetic observations in the stellar-mass regime.