Originally shared by annarita ruberto
Gravitational Waves: LIGO Picks Up on the Third Ring
The LIGO collaboration reports its third detection of gravitational waves coming from the merger of two black holes.
Once is chance, twice is coincidence, thrice is a pattern.☺
After detecting two gravitational-wave signals in September and December of 2015, the LIGO (Laser Interferometer Gravitational-Wave Observatory) Scientific and Virgo Collaborations are now reporting their third catch.
On 4 January 2017, the LIGO instruments recorded a gravitational-wave “chirp” from the merger of two black holes whose combined mass is 50 times that of the Sun.
Detailed analysis of the event—named *GW170104*—suggests a merger of two black holes having 31 and 19 solar masses. The researchers have estimated the distance to this cataclysm to be 3 billion light years, which is roughly twice as far as the two previously observed events.
The two previous gravitational-wave detections by LIGO were also black hole mergers: the first had a total mass of 65 solar masses (see 11 February 2016 Viewpoint), while the second had 22 solar masses.
These detections, along with GW170104, provide an estimate of the merger rate of stellar-mass binary black holes, and the rate appears to be larger than some models predict.
The observations also give insight into the typical properties of binary black holes, including their spins. Spins are difficult to measure, but results from GW170104 suggest that the spins may not be aligned with the pair’s mutual orbit, a finding that could favor some black hole binary formation mechanisms over others.
► Source>>
https://physics.aps.org/synopsis-for/10.1103/PhysRevLett.118.221101
► The study “GW170104: Observation of a 50-Solar-Mass Binary Black Hole Coalescence at Redshift 0.2” is published in Physical Review Letters>> https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.118.221101
► Here the PDF paper>> https://dcc.ligo.org/public/0140/P170104/012/LIGO-P170104_Detection_of_GW170104.pdf
► Image credit: LIGO/Caltech/MIT/Sonoma State (A. Simonnet)
Further reading
► Gravitational waves: Third detection of deep space warping>> http://www.bbc.com/news/science-environment-40120680
#Astrophysics, #LIGO_Collaboration, #GravitationalWaves, #Research, #BlackHoles