first observation of a black hole waking up live

We are witnessing for the first time the awakening of a black hole. Astrophysicists saw this black hole, located about 300 million light years from Earth, become activated: suddenly, the gases around it became very bright.

It is a phenomenon that we have been trying to observe for a long time, to understand how the black holes that reign at the heart of galaxies structure them: the awakening of a black hole. Mathilde Fontez, editor-in-chief of the scientific magazine Epsiloon, returns to this observation which has just been published by an international team of astrophysicists.

franceinfo: These astrophysicists followed the awakening of this black hole live?

Mathilde Fontez: Yes, they saw a black hole which suddenly began to swallow the gas around it, which began to attract it, heat it, until it began to shine to the point of being visible hundreds of millions of light years away.

A black hole which until then was calm, like ours, the one which reigns at the center of our galaxy, but which has awakened, under the lens of telescopes.

A stroke of luck…

Yes, astronomers have admitted it. They had launched detection campaigns, they had even targeted particular galaxies, whose light seemed to vary. They were looking for this phenomenon: in the universe, 10% of galaxies have a very bright center, a heated center, illuminated by the monstrous gravity of a central black hole.

But the astronomers had not stumbled upon the rare gem: a galaxy where we see the phenomenon starting. And it was a routine observation, from the Zwicky telescope in California, which found it, first in 2019. A first sign of enlightenment, 300 million light years from us. Then in 2022, it got worse.

So astronomers brought out the heavy artillery, the largest telescopes in the world, the Keck in Hawaii and the Very Large Telescope in Chile. And they could see that this bright light continued to intensify. “Unprecedented behavior”according to the researchers. For the first time, we see the activation of a supermassive black hole, in real time.

And it continues ?

Yes, and this is what makes specialists say that it is not simply a question of a star which passed by there, near the black hole, and which was torn apart. If that were the case, it should be over – this kind of star attack only lasts a few weeks, a year at most. No, it seems that here, the black hole is lighting up the entire center of its galaxy.

Enough to understand the phenomenon, know why it occurs, what triggers it. And for example, predict if our black hole, Sagittarius A*, could one day wake up, and light up the entire center of our galaxy.