The signal was produced by the merger of two massive black holes, weighing 31 and 25 times the mass of the Sun at a distance of 1.7 billion light years away from us. An energy equivalent to the mass of three Suns was radiated as gravitational waves in this energetic astronomical event. These detections of gravitational waves from merging black hole pairs allow us to map out the distribution of black holes in the universe and to do precision tests of Einstein’s theory of General Relativity. Results from this detection are presented in a new paper accepted for publication in the journal Physical Review Letters.
The LIGO-Virgo collaboration includes more than a thousand scientists from many different countries, setting a great example in international scientific cooperation. The recent publication has 40 authors from 13 Indian institutions. Over the last three decades, Indian scientists have done foundational work in various aspects of gravitational-wave science, including theoretical calculation of expected signals from astronomical sources, developing sophisticated data analysis techniques for searching weak gravitational-wave signals in noisy data and devising techniques to combine data from multiple detectors. The current Indian team in the LIGO-Virgo collaboration has made direct contributions to the extraction of the properties of the astronomical source from the data and to the first tests of Einstein’s theory using these observations. The Indian contribution to this emerging frontier will grow significantly in the future, with the materialisation of the LIGO-India observatory, which is being built on Indian soil. This is expected to bring manyfold improvements to the source localisation accuracy.
This three-dimensional projection of the Milky Way galaxy onto a transparent globe shows the probable locations of the three confirmed black-hole merger events observed by the two LIGO detectors—GW150914 (dark green), GW151226 (blue), GW170104 (magenta)—and a fourth confirmed detection (GW170814, light green, lower-left) that was observed by Virgo and the LIGO detectors. Also shown (in orange) is the lower significance event, LVT151012. The outer contour for each represents the 90 percent confidence region; the innermost contour signifies the 10 percent confidence region. The addition of Virgo shows a dramatic increase in the sky localization. [Image credit: LIGO/Virgo/Caltech/MIT/Leo Singer (Milky Way image: Axel Mellinger)]
LIGO is funded by the NSF, and operated by Caltech and MIT, which conceived and built the project. Financial support for the Advanced LIGO project was led by NSF with Germany (Max Planck Society), the U.K. (Science and Technology Facilities Council) and Australia (Australian Research Council) making significant commitments and contributions to the project. More than 1,200 scientists from around the world participate in the effort through the LIGO Scientific Collaboration, which includes the GEO Collaboration. Additional partners are listed at http://ligo.org/partners.php.
The Virgo collaboration consists of more than 280 physicists and engineers belonging to 20 different European research groups: six from Centre National de la Recherche Scientifique (CNRS) in France; eight from the Istituto Nazionale di Fisica Nucleare (INFN) in Italy; two in The Netherlands with Nikhef; the MTA Wigner RCP in Hungary; the POLGRAW group in Poland; Spain with the University of Valencia; and EGO, the laboratory hosting the Virgo detector near Pisa in Italy.Indian Institutions involved in the current work, and corresponding contact persons:
IndIGO-LSC Principal Investigator
Bala Iyer (ICTS) E-mail: bala.iyer at icts.res.in, Tel. 9739373144LIGO-India spokesperson:
Tarun Souradeep (IUCAA) E-mail: tarun at iucaa.in, Tel. 9422644463IUCAA - Inter University Centre for Astronomy and Astrophysics, Pune
Sanjit Mitra E-mail: sanjit at iucaa.in, Tel. 8275067686RRCAT - Raja Ramanna Centre for Advanced Technologies, Indore
IPR - Institute for Plasma Research, Gandhinagar
CMI - Chennai Mathematical Institute
K G Arun E-mail: kgarun at cmi.ac.in, Tel. 9500066350ICTS - International Centre for Theoretical Sciences (TIFR), Bengaluru
P. Ajith E-mail: ajith at icts.res.in, Tel. 9164594474TIFR - Tata Institute of Fundamental Research, Mumbai
A. Gopakumar E-mail: gopu at tifr.res.in, Tel. 9869039269C. S. Unnikrishnan E-mail: unni at tifr.res.in, Tel. 9869564290
IISER-Kolkata - Indian Institute of Science Education and Research Kolkata
Rajesh Kumble Nayak. E-mail: rajesh at iiserkol.ac.in, Tel. 9903507977IISER-TVM - Indian Institute of Science Education and Research Thiruvananthapuram
IIT Bombay - Indian Institute of Technology Bombay
Archana Pai E-mail: archanap at iitb.ac.in, Tel. 9037573123Varun Bhalerao E-mail: varunb at iitb.ac.in, Tel. 9850005899