Submitted by alvin on Thu, 2016-06-16 01:06 Bengaluru: It’s official. Scientists of the Laser Interferometric Gravitational-wave Observatory (LIGO) project, who discovered the first gravitational wave (GW) in February, have now discovered a second one, in quick succession. The announcement about the same was made in the US at 10.45pm IST. A member of the project said the discovery of waves in such quick succession opened new ways of doing astronomy. The detection of the two gravitational wavesin succession, well before the detectors reaching their target sensitivity, underlines immense possibilities in gravitational physics. The second wave was picked up by the LIGO detectors in Hanford, Washington and Livingston, Louisiana on December 26, 2015 at 9.09am IST through a signal from the coalescence of two black holes, with masses 14 and 8 times the mass of the sun, merging into a more massive, rapidly rotating black hole that is 21 times the mass of the sun. Compared to the black holes in the first merger event, which was detected in September 2015, the latest one is much less massive. However, they said that the detection of such events posed great challenges as the signals were intrinsically weaker and their power was distributed over a longer stretch of time, hiding the signal deep inside the noise. According to the project scientists, the event happened approximately 1.4 billion years ago. During the detection process, which lasted in LIGO's frequency band for about a second, a quantity of energy roughly equivalent to the mass of the sun was radiated as gravitational wave. “In comparison, only a tiny fraction of the sun's mass gets converted to light over its entire lifetime,” a statement issued here said. The group of sciensts led by Sanjeev Dhurandhar at IUCAA, Pune, did foundational work on developing the data-analysis techniques used to detect these weak signals buried in the detector noise, while the group at RRI, Bengaluru led by Bala R Iyer collaborated with a team of French scientists did the theoretical modeling of gravitational-wave signals from orbiting black holes. The Indian scientists were also actively involved in testing Einstein’s theory of general relativity using the LIGO observations. Some of the computations needed for deciphering the discovery were performed using ICTS’s high-performance computing facilities. Thirty nine researchers from India (including 7 from ICTS) were involved in this discovery through the IndIGO consortium, which includes scientists from 9 institutions — CMI Chennai, ICTS-TIFR Bangalore, IISER Kolkata, IISER Trivandrum, IIT Gandhinagar, IPR Gandhinagar, IUCAA Pune, RRCAT Indore and TIFR Mumbai.