Sagittarius A*: A black hole at the centre of the Milky Wayhttps://indianexpress.com/article/explained/sagittarius-a-a-black-hole-at-the-centre-of-the-milky-way-6019050/

Sagittarius A*: A black hole at the centre of the Milky Way

Why has its recent behaviour intrigued scientists?

It may be that the Sagittarius A* has become hungrier, and has been feeding on nearby matter at a markedly faster rate, which one researcher described as a “big feast”.

A supermassive black hole sits 26,000 light years away from Earth, near the Galactic Centre, or the centre of the Milky Way. Called Sagittarius A*, it is one of the few black holes where we can witness the flow of matter nearby. Since the discovery of Sagittarius A* 24 years ago, it has been fairly calm. This year, however, Sagittarius A* has shown unusual activity, and the area around it has been much brighter than usual. In research published recently in The Astrophysical Journal Letters, scientists have sought to explain why this is happening.

It may be that the Sagittarius A* has become hungrier, and has been feeding on nearby matter at a markedly faster rate, which one researcher described as a “big feast”. A black hole does not emit light by itself, but the matter that it consumes can be a source of light. A large quantity of gas from the S0-2 star, which travelled close to the black hole last year, may now have reached the latter. Other possibilities of the heightened activity, the paper says, are that Sagittarius A* could be growing faster than usual in size, or that the current model that measures its level of brightness is inadequate and is in need of an update.

The researchers noted three extraordinary occasions this year that marked the black hole’s unusual behaviour. On May 13, the area immediately outside Sagittarius A* was twice as bright as compared to any previously recorded instance. Reprocessed recordings from previous years reaffirmed that the brightness had indeed increased.