Astronomy and astrophysics

Black hole spotted in the centre of the Milky Way

A black hole 100,000 times the mass of the Sun seems to be lurking near the core of our Galaxy.

Astrophysicists have long theorized the existence of supermassive black holes at galactic cores, built by successive mergers of intermediate-mass black holes, but no such objects have yet been confirmed. Tomoharu Oka of Keio University in Yokohama, Japan, and his colleagues used the ALMA radio telescope in Chile to observe a cloud of molecular gas that previous observations had suggested contained fast-moving gas swirling around a small object. ALMA’s high-resolution images revealed a point-like source of radio-wave emission and a clump of gas at its centre — consistent with a black hole roughly 100,000 times as massive as the Sun.

The black hole could be the remnant of a dwarf galaxy that was swallowed up by the Milky Way, lending credence to the merger scenario of supermassive-black-hole formation, the authors suggest.