IIT Guwahati and ISRO Researchers Detect Polarised Emissions from a Black Hole

Guwahati: In a major breakthrough, researchers from Indian Institute of Technology, Guwahati (IIT Guwahati) and UR Rao Satellite Centre, Indian Space Research Organisation for the first time, detected polarised emissions from a black hole source that exists beyond our Milky Way Galaxy using a technique called X-ray polarimetry.

Prof Santabrata Das, Department of Physics in the IIT Guwahati said, “X-ray polarimetry is a unique observational technique to identify where radiation comes from near black holes. LMC X-3 emits X-rays that are 10,000 times more powerful than those from the Sun. When these X-rays interact with the material around black holes, specifically when they scatter, it changes the polarization characteristics, i.e. degree and angle. This helps in understanding how matter is drawn toward black holes in the presence of intense gravitational forces.”

Large Magellanic Cloud X-3 (LMC X3) is a binary star system consisting of a black hole and a ‘normal’ star that is much hotter, bigger, and more massive than the Sun. It is located in a satellite galaxy of our Milky Way, nearly 200,000 light-years away from Earth. Since its discovery in 1971, it has been observed by various satellites.

In a statement issued by IIT Guwahati Dr Anuj Nandi, Scientist, U. R. Rao Satellite Centre (URSC), ISRO said, “Intense gravitational fields can cause the emitted light from black holes to become polarized. Our observations indicate that LMC X-3 likely harbours a black hole with low rotation rate, surrounded by a slim disc structure that gives rise to the polarized emissions.

The study has been published in the Monthly Notices of the Royal Astronomical Society Letters and has opened a new window to investigate and understand the nature of astrophysical black hole sources. It was funded by the Science and Engineering Research Board (SERB), Department of Science and Technology, India.