The cosmic weather could turn stormy in just over three months, the expected date of the merger between two supermassive black holes.
Astronomy is a long-term job where the policy of small steps is queen; it is often necessary to chain many rather off-putting observations before coming across an interesting element. But sometimes, at the turn of a routine observation, Lady Luck points the tip of her nose to the other side of the telescope. This is what happened to researchers at the University of Science and Technology of China, whose researchers announce that they have spotted the harbingers of an extremely rare event: the merger of two supermassive black holes.
This category includes the three most massive blacks ever spotted; they are traditionally several tens of millions, even billions of times heavier than our good old Sun. A size that is enough to make them major players in the cosmos; they serve in particular as an anchor point for the vast majority of large observable galaxies. These titans with a gargantuan appetite are therefore the subject of particular interest on the part of the scientific community.
An event never before observed live
The mere fact of finding a pair of these monsters capable of swallowing a raw neutron star in the same area, as claimed by Chinese researchers, is therefore already a remarkable event. But when they sought to model the sequence of events, they felt that a real cosmic cataclysm on a pharaonic scale was preparing: according to them, the two black holes are preparing to merge with a bang in a hundred days.
It is quite simply a rare event for many reasons. So rare, in fact, that no astronomer has it never observed live, even though there are entire laboratories dedicated exclusively to tracking down black holes. It therefore goes without saying that the publication of this work triggered a real uproar among the specialists, who wouldn’t miss the show for anything in the world.
Yet, despite the frenzy that followed the publication of the paper, a considerable amount of uncertainty remains. Indeed, the signals reach us from a region of the cosmos located 1.2 billion light-years from Earth. They are therefore by definition difficult to capture, and just as difficult to interpret. Some observers therefore remain skeptical, and suggest that it could simply be a supermassive black hole, certainly very large, but solitary.
Excitement Despite Doubt
However, these doubts were not enough to calm the enthusiasm of the researchers, which speaks volumes about the potential of this observation. Despite this general caution, the prestigious magazine Science explains that all the big names in the discipline have rushed to reserve observing time with the most powerful telescopes in the world.
Because if this is confirmed, the event could provide answers to critical questions, such as the growth of black holes. Because if we are just beginning to identify some of their physical properties, their origin and their future still remain quite mysterious. Today, no one can say with certainty by what mechanism supermassive black holes become so huge.
However, there are hypotheses that try to explain it. We know that they tend to peck their galaxies from the inside, but this is not enough to explain their mass. Many physicists therefore believe that these giants are born from the merger of several black holes. Observing this event would give them some answers to determine if it is this cannibalism that generates supermassive black holes.
This is all the more important because knowledge of these giants has implications for our overall understanding of the laws that govern the cosmos. Progress on the question of black holes would thus make it possible to (re)test Einstein’s theories, to explore the link between general relativity and quantum physics, to better understand certain aspects of the formation of stars and galaxies… and so on.
Suffice to say that the stakes are too high to risk missing this event, even if it remains uncertain. Now the bets are off; these two giants will eventually merge? The answer to the next episode, during the month of May!
The text of the study is available here.