Our understanding of the formation of the Universe to be reviewed?
Image of the six candidate massive galaxies that would have appeared from 500 to 700 million years after the big bang.
The James Webb Space Telescope observed in the remote ages of the Universe a population of very massive galaxies seeming to be similar. be formed at a much faster rate than predicted by astronomers, according to a study published Wednesday.
This puzzling scenario, which further analyzes will have to confirm, occurred between 500 and 700 million years only after the big bang that occurred 13.8 billion years ago, when the x27;Universe was very young.
The James Webb Telescope (JWST), operational since July 2022, was able to explore this little-known region thanks to its NIRCam instrument and its powerful vision in the x27;infrared, a wavelength invisible to the human eye and whose observation allows you to go far back in time.
Images of six candidate massive galaxies. One of them (bottom left) could contain as many stars as our Milky Way, but it is 30 times more compact.
He unearthed six galaxies much more massive than expected in this primordial Universe, reports a study published in Nature (in English). Two of them had already been pointed by the Hubble telescope, but had gone unnoticed as the light emitted was weak.
According to the interpretation of the new images from the James Webb Telescope, these six galaxies – called candidates at this stage, because the discovery will have to be confirmed by spectroscopy measurements – contain many more stars than expected. One of them is said to contain up to 100 billion.
That's about the size of the Milky Way, which is crazy, Ivo Labbé, first author of the study, told AFP.
It took our galaxy 13.8 billion years to form this many stars, when this young galaxy would have done the same in just 700 million years, or 20 times faster, develops this researcher from the Swinburne University of Technology, Australia.
Such distant galaxies of this size have no place in the model current cosmology that attempts to understand the structure of the Universe.
“The theory tells us that in those early ages the galaxies were very small and grew very slowly. They could typically be expected to be 10 to 100 times smaller in terms of the amount of stars.
— Ivo Labb, Swinburne University of Technology
Finding ones this big is like jumping from x27;a cliff in his eyes.
What would be wrong? The suspect could well be dark matter, the mysterious invisible matter that inhabits the Universe. While scientists can't detect it, they know its behavior pretty well and know that it plays a key role in galaxy formation.
Dark matter must x27; fit together to form a halo that attracts towards it the gas from which the stars will be born, deciphers Professor Labbé. However, this coagulation process is supposed to take a long time.
It would therefore seem that things have particularly accelerated in this primordial Universe, which would have been more efficient than what we thought for making stars, comments David Elbaz, astrophysicist at the Atomic Energy Commission (CEA) , who did not take part in the study.
Which could be explained by the expansion process of the Universe accelerating faster than we thought, notes this scientist involved in the telescope observation program developed by NASA.
The topic stirs up debate among cosmologists and this discovery is all the more exciting as it is one more indication that the model is cracking, analyzes David Elbaz.
Europe's Euclid space telescope, due to be launched into orbit this summer in an attempt to unlock the secrets of dark matter, should help unravel the mystery, he points out.
Pr Labbé cites the black swan theory, according to which an unpredictable and improbable event, if it occurs, has a considerable impact. If only one of the six candidate galaxies is verified, the theory will have to be reviewed.
