Indian scientists part of international team that discovers first-of-its-kind intermediate mass black hole
An intermediate mass blackhole consists of mass in the range of 100 to more than 1,000 solar masses. It tends to be bigger than stellar black holes with a mass range within 100 solar masses.Updated: Sep 07, 2020 15:56 IST
An international team of gravitational wave astronomers from LIGO Scientific and Virgo collaboration have discovered a first-of-its-kind intermediate mass black hole formed by the merger of two massive black holes that resulted in gravitational waves. The team included researchers from Indian scientific and research institutes like the Indian Institutes of Technology (IITs), Indian Institute of Science Education and Research, (Kolkata and Pune) and Inter-University Centre for Astronomy and Astrophysics, Pune,
An intermediate mass blackhole consists of mass in the range of 100 to more than 1,000 solar masses. It tends to be bigger than stellar black holes with a mass range within 100 solar masses and smaller than the massive entities of million-odd solar masses.
“LIGO (Laser Interferometer Gravitational-wave Observatory) detectors observe the signals sent by the gravitation waves formed during the formation of a black hole and the discovery of this particular black hole is important because this is the first time that we got very clear evidence of the existence of intermediate mass black holes,” said Archana Pai, professor, physics department, IIT-Bombay. Pai and a PhD student from the institute, Koustav Chandra, were actively working on this project for the past one year.
The latest discovery will help scientists and astrophysicists understand the formation of extremely large black holes such as the present one.
On May 21, 2019, LIGO detectors at Hanford, Washington and Livingston, Louisiana and the advanced Virgo detector in Cascina, Italy, detected a signal from the most massive black hole merger yet observed in gravitational waves, or ripples, in space and time.
The gravitational wave event – GW190521 – is the gravitational wave signal emitted during the collision of two black holes of mass 85 and 66 times the mass of our Sun in the binary system, forming a remnant black hole of mass 142 times the mass of the Sun. It was generated by a source that is roughly 5 gigaparsecs away when the universe was about half its age, making it one of the most distant gravitational-wave sources detected so far.
Researchers took a year to analyse and confirm its existence; results of which were published in Physical Review Letters and The Astrophysical Journal Letters on September 2.
“As per our conventional knowledge of black holes, they either belong to stellar-mass category formed from the collapse of a single heavy star or super-massive blackholes like those found at the centre of galaxies. This new particular discovery seems to suggest a third kind, the intermediate mass black hole, which is the first-of-its-kind ever detected in LIGO,” said Anand Sengupta, associate professor of physics at IIT Gandhinagar.
The gravitational research groups of several Indian institutes play important roles in gravitational wave detections. The Indian team in the LIGO Scientific Collaboration (LISC) includes scientists from various institutes such as the Chennai Mathematical Institute, International Centre for Theoretical Sciences-Tata Institute of Fundamental Research (TIFR) in Bengaluru, Institute of Plasma Research, Gandhinagar, Raja Ramanna Centre for Advanced Technology Indore, Saha Institute of Nuclear Physics, Kolkata and TIFR, Mumbai.
“Previously, black holes under 100 solar masses have been discovered and there has been enough evidence for super massive black holes such as galaxies with million solar masses, but never has there been any discovery of an intermediate mass black hole of between 100-1000 solar masses,” said Chandra Kant Mishra, assistant professor, Physics department, IIT Madras.
Data suggests that it would be a merger of two black holes that has produced the 142 solar mass intermediate black hole, but scientists feel that there could also be the possibility of a different source for the formation of such an entity like the collapsing of a massive star that could lead to a similar reaction.
“Collision of two smaller black holes leading to the formation of this intermediate mass entity is our best guess as of now, and we are still intrigued by the same. This evidence could lead to more interesting information and we (researchers) are very excited to learn more,” added Mishra.
Dr. Santabrata Das, Associate Professor, Department of Physics, IIT Guwahati called the discovery remarkable. “So far, the possible existence of more than 300 intermediate mass blackhole was reported in literature, however, all these detections were indirect in nature as these claims were based on circumstantial evidence. This time the detection is direct and the measured black hole mass in just below 150 Solar mass. With this discovery, Scientists would be engaged to unveil this mystery,” he said and added that this discovery opens up a new window to understand the properties of a class of the black hole having a mass range of 30-100000 Solar mass. “This is really exciting altogether in terms of Science progress.”
The possibility of a better understanding of the origin of intermediate massive black holes based on the research of this particular event has excited the entire astrophysics community. “As we see more and more such big massive black hole collisions, we might get some clue on the intermediate mass black hole population,” said Pai.
A century after Albert Einstein first predicted gravitational waves in 1916, the Laser Interferometer Gravitational-Wave Observatory (LIGO) Scientific Collaboration - comprising of 1,006 members from 15 countries including India - announced the discovery of gravitational waves in February 2016.