In space, black holes dance

franceinfo: What is this amazing scene?

Herve Poirier: Imagine these two dark stars hidden in a cocoon of stars approaching each other as their galaxies begin to merge. Then they turn around, leaving a trail of stars behind them, faster and faster, violently hurling the stars between them, before they melt into one another, into a larger pit. This cosmic sphere is so extreme that astrophysicists couldn’t even model it. So much so that they weren’t sure that such a merger could actually happen. However, this is what four teams of astrophysicists believe they have observed independently: European, Australian, North American, and Chinese.

What exactly did these teams see?

Meaning nothing, since black holes are completely dark spheres, the centers of matter are impenetrable, and they are so dense that they allow nothing to escape, not even light. Scientists have rather heard the sound of the ball: they have felt the gravitational effect of this merger, which vibrates the frame of space-time. Since 2015, thanks to the detectors Lirgo and Vigo, several black hole mergers have been detected thanks to these “gravitational waves”. But it was just a small black hole, saddled with a few suns.

And this time?

Supermassive fusion causes space-time to vibrate much more slowly: the detected wave frequency is of the order of one pulse every billionth of a second. This vibration seems to come from all directions in the sky, which means that there are hundreds of thousands of such events going on around us. Right now, the signal is too weak to eliminate the possibility of random noise. Researchers are also not sure that it corresponds to the dance of these monsters. But this is the most likely explanation they currently offer. Notes will continue.