GW170608: Observation of a 19 Solar-mass Binary Black Hole Coalescence

Abstract

On 2017 June 8 at 02:01:16.49 UTC, a gravitational-wave (GW) signal from the merger of two stellar-mass black holes was observed by the two Advanced Laser Interferometer Gravitational-Wave Observatory detectors with a network signal-to-noise ratio of 13. This system is the lightest black hole binary so far observed, with component masses of 12 − 2 + 7 M ⊙ and 7 − 2 + 2 M ⊙ (90% credible intervals). These lie in the range of measured black hole masses in low-mass X-ray binaries, thus allowing us to compare black holes detected through GWs with electromagnetic observations. The source’s luminosity distance is 340 − 140 + 140 Mpc , corresponding to redshift 0.07 − 0.03 + 0.03 . We verify that the signal waveform is consistent with the predictions of general relativity.

The Polarizations of Gravitational Waves

“…Or, one can also use R tjtk to label different polarizations.Tthe plus mode is labeled bŷ P + = −R txtx + R tyty , the cross mode is byP × = R txty , the transverse breathing mode is donated bŷ P b = R txtx + R tyty , the vector-x mode is donated byP xz = R txtz , the vector-y mode is given byP yz = R tytz , and the longitudinal mode is given byP l = R tztz . According to the E(2) classification, the longitudinal mode (Ψ 2 = 0) belongs to Class II 6 , so all six polarizations exist in some coordinate systems. One can apply the E(2) classification to some paricular modified theories of gravity.…”

“…The gravitational wave (GW) was detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO) Scientific and Virgo collaborations, which further supports General Relativity (GR) [1][2][3][4][5][6]. It is also a new tool to probe gravitational physics in the high speed, strong field regime.…”

Localization of binary neutron star mergers with second and third generation gravitational-wave detectors

“…Unlike most EM telescopes, GW detectors are not pointing instruments, and localization is achieved primarily by measuring the differences in arrival times of the signal in different detectors [51]. Consequently, searching the relatively large GW localization regions (Oð100-1000 deg 2 Þ for the first detections [11,52,53]) represents a challenge for even wide field of view UV, optical and infrared telescopes. These telescopes have fields of view on the order of 10 deg 2 or less [54][55][56].…”

Moduli stars

“…The density of the star is encoded in the compactness parameter 13) whereC ≡M /R is the dimensionless compactness. 4 It follows that the overall densest objects are typically those with Λ = M P : for a fixed value ofC the compactness is suppressed by a factor of (Λ/M P ) 2 . Given a fixed value of the scale Λ, stars with larger core amplitude are denser, as we will show explicitly in section 3.2.…”

“…Collisions of black holes [2][3][4][5] and neutron stars [6] have been observed and a plethora of new events, even involving new physics, are expected to be detected in the next few years. Furthermore, the on-going search for new compact objects such as exo-planets will provide vast amount of new data over the upcoming decades (e.g.…”