IIT Guwahati, ISRO and Israeli team detect rare X-ray flickers from distant black hole

Indian Researchers Detect Rare X-Ray Signal from Distant Black Hole (Representational Image: Canva)

A group of Indian and Israeli researchers has discovered a strange X-ray pulse blinking from a faraway black hole, shedding new light on its enigmatic behaviour.

Unusual Pattern Seen in Black Hole GRS 1915+105

The black hole, named GRS 1915+105, is located almost 28,000 light-years away. Using India’s AstroSat observatory, researchers spotted alternating bright and dim X-ray phases. Each phase lasted several hundred seconds, revealing critical changes in the hot corona around the black hole. During bright phases, the corona became smaller and hotter, releasing rapid flickers nearly 70 times a second. These fast flickers vanished during dimmer phases, when the corona expanded and cooled.

Flickering Linked to Changing Black Hole Corona

Professor Santabrata Das from IIT Guwahati explained the bright phases show compact and energetic activity near the event horizon. The team found that the rapid 70 Hz flickering appeared only in these brighter states, linking the signal to shifts in the corona’s size and energy. This showed the corona is not fixed but changes constantly with the inflow of gas.

Significance for Black Hole and Galaxy Studies

Dr Anuj Nandi from ISRO’s U R Rao Satellite Centre said the finding provides direct evidence for the origin of X-ray flickering. The study, co-authored with Haifa University researchers, was published in the Monthly Notices of the Royal Astronomical Society. Researchers think the discovery clarifies knowledge of how black holes develop and release energy. It also provides insight into how black holes structure galaxies by controlling the flow of radiation and matter in space.