Tsinghua University advanced computing research group contributed to gravitational wave detection from second pair of colliding black holes
On June 15, 2016, the Laser Interferometer Gravitational-wave Observatory (LIGO) Scientific Collaboration and the Virgo collaboration announced that a second gravitational wave event was identified in the data from Advanced LIGO detectors, at the 228th meeting of American Astronomical Society, San Diego, California, USA. As a LIGO Scientific Collaboration member, Tsinghua University advanced computing research group participated in this effort.
A comparison of two gravitational wave events: GW150914 and GW151226. These black holes as the GW151226 source were much less massive than those in the first detection GW150914. Because of their lighter mass, they spent more time – about one second – in the sensitive band of the detectors. The GW150914 signal swept upwards in frequency from 35 Hz to 250Hz and GW151226 from 35 to 430Hz.
On December 26, 2015 at 03:38:53 UTC, scientists observed gravitational waves—ripples in the fabric of spacetime—for the second time. The gravitational waves were detected by both of the twin Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington, USA.
The LIGO Observatories are funded by the National Science Foundation (NSF), and were conceived, built, and are operated by Caltech and MIT. The discovery, accepted for publication in the journal Physical Review Letters, was made by the LIGO Scientific Collaboration (which includes the GEO Collaboration and the Australian Consortium for Interferometric Gravitational Astronomy) and the Virgo Collaboration using data from the two LIGO detectors.
Gravitational waves carry information about their origins and about the nature of gravity that cannot otherwise be obtained, and physicists have concluded that the detected gravitational waves once again were produced during the final moments of the merger of two black holes—14 and 8 times the mass of the sun—to produce a single, more massive spinning black hole that is 21 times the mass of the sun. During the merger, which occurred approximately1.4 billion years ago, roughly the equivalent of the mass of the sun was converted into gravitational waves. The detected signal comes from the last 27 orbits before the merger. The arrival time of the signals, with the Livingston detector measuring the waves 1.1milliseconds before the Hanford detector, gives a rough idea of the position of the source in the sky.
Professor Junwei Cao is now in charge of the LIGO Scientific Collaboration research group at Tsinghua University. The group is focused on improvement of performance and efficiency of gravitational wave data analysis using advanced computing technology, significantly contributing to the two gravitational waves detections so far. Not long ago, the 2016 Special Breakthrough Prize in Fundamental Physics was awarded to contributors of direct detection of gravitational waves.
