Was the black hole observed to become active?

A distant galaxy that suddenly became brighter may have allowed researchers to watch a massive black hole in action. The European Southern Observatory (ESO), based in Garching near Munich, said such a change had not been observed before.

At the end of 2019, the previously blurry galaxy SDSS1335+0728 was said to have become noticeably brighter. The galaxy, located about 300 million light-years away in Virgo, is currently continuing to increase in brightness. The galaxy emits more light in the optical range, but also in the ultraviolet and infrared range. It has also been emitting X-rays for several months. “This behavior is unprecedented,” commented astronomer Paola Sanchez Saez.

Activate the black hole in real time

Sanchez Saez's research team suspects that the center of the galaxy – a massive black hole – has come into play. “If so, this would be the first time we have seen a massive black hole activate in real time,” said co-author Lorena Hernandez-Garcia. Astrophysicist Claudio Ricci added that black holes are usually “dormant” and not directly visible.

Black holes are objects with gravity so strong that even light cannot escape. They are formed when large stars with a mass several times the mass of our Sun explode in the form of supernovas at the end of their existence and the remaining star collapses.

Massive or supermassive black holes are suspected to exist at the centers of most galaxies. Its mass could be billions of times greater than the mass of our Sun. The most massive in our galaxy is Sagittarius A* at the center of the Milky Way, which is about four million times the mass of the Sun. According to Ritchie, this black hole could also become active. According to Eso, it is unclear how likely this is. The observational analyzes were published in the journal Astronomy and Astrophysics.