Articles and discoveries are multiplying about ancient galaxies that can now be well observed by James-Webb, Hubble’s successor, and which do not seem to really fit the predictions of the standard cosmological model, although the debate is far from over. . The latest discovery concerns a galaxy four times more massive than the Milky Way, just 2 billion years after the Big Bang.
We know that the Standard Cosmological Model is based on the existence of particles that have never been seen before and that should not be able to emit light, or much less, but should be able to act on known particles, such as baryons, which are protons. . and neutrons, through the gravitational interaction. of detectors LHCLHC Mu CERNCERN Try to see them in the collision products between the proton beams of this large particle accelerator, but its particles black matterblack matter What are you doing CosmologyCosmology Perhaps so large that it would be necessary to make them, according to the famous relation ofEinsteinEinstein E = mc2go up to EnergyEnergy That would require a collider with a radius of about 100 km.
In the meantime, we are still looking for new clues to the existence and properties of dark matter particles galaxiesgalaxies NoEdwin HubbleEdwin Hubble. For the moment, these particles are still almost the only way to give birth to the galaxies we observe and bring them together. Galaxy clusterGalaxy cluster grouped into filaments. We don’t really know how to reproduce the characteristics of the fossil radiation from the Big Bang discovered by Penzius and Wilson without these dark matter particles.
But we also know that there is DiscrepanciesDiscrepancies Or features of galaxies that we can better understand if we do without dark matter particles and use changes to the laws of celestial mechanics. NewtonNewtonThis theory was already put forward in the early 1980s by the Israeli physicist Mordechai Milgrom as part of his Modified Newtonian Dynamics, known today by the acronym Mond. However, it is currently in trouble due to observations from the Gaia satellite.
For 13.8 billion years, the universe has been evolving. Contrary to what our eyes tell us when we contemplate the sky, what makes it is far from static. Physicists make observations and simulations of the universe at different ages in which they replay its formation and evolution. It appears that dark matter played a major role from the beginning of the universe to the formation of the massive structures observed today. © CEA Research
The Milky Way is 4 times more massive than the Milky Way 11.5 billion years ago
But who knows what it’s all about?
Maybe it is James Webb Space TelescopeJames Webb Space Telescope (JWST) which will help us see things more clearly through studies like never beforeInfraredInfrared The oldest galaxies that can be observed today and in this context, this is the case of one named JWST-7329. We see it around 11.5 billion years ago (which means it was 11.5 billion years ago at present. Milk GangesMilk Ganges The spectral shift of which can be calculated online thanks to cosmologist New Wright, here as z = 3.2 AstrophysicistsAstrophysicists in their language. Then we find a distance of about 21 billion todaylight yearslight years).
JWST-7329 is the subject of an article published in a renowned journal Nature and which may be consulted freely arXiv. It outlines the work of an international team that used JWST, led by Carl Glazebrook of Swinburne University of Technology in Melbourne, Australia.
In the university’s press release about JWST-7329, Carl Glazebrook explains: “ We’ve been tracking this galaxy for seven years and spent hours observing it with two of the largest telescopes on the planet to determine its age. But it was too red and too pale, and we couldn’t measure it. Eventually, we had to leave Earth and use JWST to confirm its nature. It was largely a team effort, with many of our hours since the infrared sky studies we began in 2010 allowing us to identify this galaxy as unusual. CakeCake And A very large telescopeA very large telescope Where we tried to confirm it was until last year when we made a huge effort to figure out how to process and analyze the JWST data, but failed. spectraspectra. »
Are galaxies too massive for dark matter cosmology?
The result is that JWST-7329 is already 11 billion years older than the Milky Way and contains manythe starsthe stars At that time already 1.5 billion years old.
Although it seems that such a galaxy would not have had time to form, the dark matter was not yet sufficiently concentrated by it. DownfallDownfall Gravitational forces collapsed baryonic matter fast enough to form JWST-7329, another example of a galaxy discovered by James-Webb 11 billion years ago.
This was explained by Claudia Lagos of the University of Western Australia’s International Center for Radio Astronomy Research (ICRAR), who played a crucial role in its development. ModelizationModelization Theory of evolution of dark matter concentration for study.
” Galaxy composition is largely determined by how dark matter is concentrated. The presence of these extremely massive galaxies so earlyuniverseuniverse poses significant challenges for us standard modelstandard model of cosmology. Indeed, we do not think there has been time to form dark matter structures massive enough to host these galaxies. More observations are needed to help understand how common these galaxies are and how massive these galaxies really are. »
In the same press release, Carl Glazebrook adds that “ JWST has discovered increasing evidence for the early formation of massive galaxies. This result sets a new record for the event. Although very attractive, it is only one case. But we hope to find out more; And if we do, it will really shake up our ideas about galaxy formation “
We know that the Mond theory predicts the early formation of large galaxies.
