For the first time, scientists have captured signals from an ancient galaxy far, far away. This wouldn't be so surprising if the galaxy in question hadn't died.
“[…] Just when we think we understand an astrophysical phenomenon, the universe […] surprises us“. The reaction of Wen-fai Fong, associate professor of physics and astronomy, is understandable. He has just noticed something that the scientific community thought it was impossible. This is not the first time that a discovery has shaken up our understanding of space. And it certainly won't be the last.
Here it is a question of FRBpour Fast Radio Burstor Rapid Radio Bursts as we call them back home. This is a radio wave pulse lasting a few milliseconds at most. During this very short period of time, the energy generated is greater than that which the Sun emits in an entire year. As they progressed, the researchers came to the conclusion that such signals could only be sent by active star clusters. They were wrong.
We have captured radio signals coming from a dead galaxy and this is a first
In February 2024, the CHIME radio telescope (Canadian Hydrogen Intensity Mapping Experiment) located in Canada captures an FRB. 21 other similar signals followed in the space of 5 months. Nothing special in absolute terms, except when we realize thatthey come from a very ancient galaxy. Don't think this is a way of speaking: she is completely dead.
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The galaxy at the origin of these FRBs is located at 2 billion light years from Earth and would be 11.3 billion years old. After simulation, it also turns out that it would be both extremely luminous and massive: 100 billion times the mass of the Sun.
“[…] We find no evidence [de l’existence] young stars in this galaxy. […] There may be a subpopulation of FRBs associated with older systems“, asks study director Tarraneh Eftekhari. This mystery leaves scientists perplexed, especially since it does not stop there.
-These “beyond the grave” FRBs still remain unexplained
What is even more surprising is that the FRBs come more precisely from the periphery of the galaxy130,000 light years from its center. “This is both surprising and exciting, because FRBs are expected to come from inside galaxies, often in regions where stars are forming. The location of this FRB so far from its host galaxy raises questions about how such energetic events can occur in regions where no new stars form.“, summarizes Vishwagi Shah of McGill University.
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Currently, the authors can only offer hypotheses by way of explanations. The most likely is that the signals come from a globular clustera very dense structure bringing together at least hundreds of thousands of stars in what looks from a distance like a sphere. Teams submitted a request to use the télescope spatial James Webb in order to be clear about it.
If this is confirmed, it will be the 2nd FRB of this type ever observed, the first having been spotted in 2022. Otherwise, “alternative exotic scenarios will have to be considered“, laughs Vishwagi Shah. As Tarraneh Eftekhar recalls, “iIt's clear that there are still many exciting possibilities for discovery when it comes to FRBs, and that their environments could hold the key to unlocking their secrets“. Until the next ones, certainly.
Source : Northwestern University
