GW150914: First results from the search for binary black hole coalescence with Advanced LIGO

On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) simultaneously observed the binary black hole merger GW150914. We report the results of a matched-filter search using relativistic models of compact-object binaries that recovered GW150914 as the most significant event during the coincident observations between the two LIGO detectors from September 12 to October 20, 2015. GW150914 was observed with a matched filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203 000 years, equivalent to a significance greater than 5.1 {\sigma}.Comment: 20 pages, 10 figure

GW150914: The advanced LIGO detectors in the era of first discoveries

Following a major upgrade, the two advanced detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) held their first observation run between September 2015 and January 2016. With a −23 pffiffiffiffiffiffi strain sensitivity of 10 = Hz at 100 Hz, the product of observable volume and measurement time exceeded that of all previous runs within the first 16 days of coincident observation. On September 14, 2015, the Advanced LIGO detectors observed a transient gravitational-wave signal determined to be the coalescence of two black holes [B. P. Abbott et al., Phys. Rev. Lett. 116, 061102 (2016)], launching the era of gravitational-wave astronomy. The event, GW150914, was observed with a combined signal-to-noise ratio of 24 in coincidence by the two detectors. Here, we present the main features of the detectors that enabled this observation. At full sensitivity, the Advanced LIGO detectors are designed to deliver another factor of 3 improvement in the signal-to-noise ratio for binary black hole systems similar in mass to GW150914

Self-traction during mechanical cervical dilatation, acceptability, feasibility and satisfaction of its application: A pilot study

This study aims to measure acceptability, feasibility, and satisfaction with self-traction during mechanical cervical dilatation to induce labour and to explore its effects on pain and the process of labour and delivery. 60 parturients were randomly assigned to self-traction or regular traction. Participants completed questionnaires about sociodemographic characteristics, acceptability, and satisfaction. Self-traction participants reported significantly higher acceptability (P = 0.026), and adequacy (P = 0.018). They also reported satisfaction with the procedure. A group comparison regarding feasibility, pain, and the process of labour and delivery showed no significant difference. Self-traction is an acceptable and feasible intervention for full-term parturients

GW150914: Implications for the stochastic gravitational-wave background from binary black holes

The LIGO detection of the gravitational wave transient GW150914, from the inspiral and merger of two black holes with masses ≳ 30 M ⊙ , suggests a population of binary black holes with relatively high mass. This observation implies that the stochastic gravitational-wave background from binary black holes, created from the incoherent superposition of all the merging binaries in the Universe, could be higher than previously expected. Using the properties of GW150914, we estimate the energy density of such a background from binary black holes. In the most sensitive part of the Advanced LIGO and Advanced Virgo band for stochastic backgrounds (near 25 Hz), we predict Ω GW ( f = 25     Hz ) = 1. 1 + 2.7 − 0.9 × 10 − 9 with 90% confidence. This prediction is robustly demonstrated for a variety of formation scenarios with different parameters. The differences between models are small compared to the statistical uncertainty arising from the currently poorly constrained local coalescence rate. We conclude that this background is potentially measurable by the Advanced LIGO and Advanced Virgo detectors operating at their projected final sensitivity.by Anand Sengupt