Team led by Indian scientists find X-ray signature of boundary around black holes

A team of international scientists, led by those from India, have found a distinctive signature of cosmic X-rays to identify boundary around black holes, which "unmistakably separate m" from or objects in cosmos such as neutron stars that are comparable in mass and size.

According to astrophysicists, including Sudip Bhattacharyya from Tata Institute of Fundamental Research (TIFR) in Mumbai, current discovery is by far strongest stey signature of smaller, but more extreme stellar-mass black holes to date, from cosmic X-rays observed with a satellite.

Although black holes does t have a surface, it is confined within an invisible boundary, called an event horizon, from within which thing, t even light, can escape, scientists said.

While definitive proof of existence of such objects is a holy grail of modern physics and astromy, y said only one supermassive black hole with mass more than six billion times mass of Sun has so far been imd using surrounding riation in rio wavelengths. But according to study, accepted for publication in journal Monthly tices of Royal Astromical Society, understanding stellar-mass black holes, which have masses about ten times that of Sun, is indispensable to probe some of extreme aspects of cosmos.

In order to prove existence of se stellar-mass black holes, researchers said se need to be distinguished from neutron stars which are densest kwn objects in universe with a hard surface. While stable stellar-mass black holes shine mainly in X-rays by devouring material from a companion star, study ted that neutron stars can also shine in X-rays by accreting matter from a companion star in a similar way.

In current study, scientists analysed archival data from w decommissioned astromy satellite Rossi X-Ray Timing Explorer, and have identified effect of lack of hard surface in black holes on ir observed X-ray emission.From this analyses, y have found an extremely strong signature of accreting stellar-mass black holes.

" study has found by far strongest stey signature of smaller, but more extreme, black holes to date, from cosmic X-rays observed with a satellite," Bhattacharyya told PTI in an email.