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[EN VIDÉO] Understanding the James Webb Space Telescope’s Mission in a Minute The James Webb Space Telescope, the new flagship of space observation, will be launched on December 18…
The Hubble Telescope allowed cosmologists to use gravitational lensing to study the state of the observable universe about 500 million years after the Big Bang. With the James-Webb, the likely limit should be around 150 million years, which should make it possible to explore the so-called reionization period, which takes us from the Dark Ages to the cosmic dawn and whose exact time it began and also we do not yet know not when it ended. Because there are variations, broadly speaking we still often agree that it occurred between 130 and 950 million years after the Big Bang.
Remember that about 380,000 years after the Big Bang, within a few thousand years, the temperature in the cosmos fell to the point where neutral atoms formed and released the famous fossil radiation. Reionization is the moment when the first stars and the first quasars have formed to the point where these atoms begin to ionize again through the radiation they emit.
We want to understand what happens during this period when dark matter collapse accelerates the collapse of known matter and creates the first galaxies that are close enough to each other to be subject to frequent tidal forces and collisions.
The standard cosmological model for a decade has consisted primarily of grown galaxies and the giant black holes they harbor, which can transform into quasars by channeling streams of cold baryonic matter via dark matter filaments that are applied to the galaxies in the process of formation and evolution fall.
The universe has continuously evolved for 13.8 billion years. Contrary to what our eyes tell us when we look at the sky, what makes it up is anything but static. Physicists make observations at different ages of the universe and run simulations in which they recreate its formation and evolution. It appears that dark matter played a large role from the beginning of the universe to the formation of the large structures observed today. © CEA Research
Simulations combining dark matter and exploding stars
To understand all these phenomena, it is necessary to carry out numerical simulations. They have become increasingly powerful and refined over the years to take into account not only the dynamics of dark matter, the largely dominant component of matter in the observable universe, but also the feedback of the dynamics of normal matter with supernovae explosions and the chemical evolution of galaxies as a result of stellar nucleosynthesis, which affects the formation of new stars (see video below).
These models are still being improved, but more than a decade ago the general consensus was that the James-Webb, when operational, should see small, few, and irregular galaxies a little less than 500 million years after the Big Bang.
This is not at all what we are observing.
At the beginning of summer 2022 there were also statements on his Twitter account by the famous American astrophysicist and cosmologist Stacy McGaugh. The latter is known for his work based on the Moon Theory, an acronym for Modified Newtonian Dynamics in English, and which therefore studies galaxies, dark matter and modified gravitational theories as an alternative to the existence of black matter.
Stacy McGaugh explained that if it were confirmed that the James Webb Telescope had seen many large galaxies early in the history of the observable cosmos, it could perhaps provide a test to refute the Standard Model of cosmology, which relies on the existence of particles based on dark matter, and secondly represent a confirmation of the moon theory.
However, in the article we dedicated to McGaugh’s statements, we also initially asked Françoise Combes and Romain Teyssier on the subject, who encouraged us to be cautious. We then interviewed one of the astronomers who wanted to observe the first galaxies together with James-Webb: Johan Richard from the Lyon Astrophysical Research Center.
In this 2016 video, Phil Hopkins, an associate professor of theoretical astrophysics at Caltech, and Andrew Wetzel, a research scientist at Carnegie-Caltech, used supercomputers to create the most detailed and realistic simulation of galaxy formation ever created. The results solved a decades-old mystery about dwarf galaxies around our Milky Way. Andrew Wetzel is part of the team that believes they have similarly replicated the James Webb results as part of the Feedback of Relativistic Environments (FIRE) project, co-founded by Faucher-Giguère. To get a reasonably accurate French translation, click on the white rectangle at the bottom right. English subtitles should then appear. Then click on the nut to the right of the rectangle, then click on “Subtitles” and finally “Auto-translate”. Select “French”. © Caltech
Bursts of new star formation stronger than expected
In this context, we understand the importance of the article published today in the Astrophysical Journal Letters by a team of astrophysicists led by Northwestern University (USA). In the university press release accompanying this release, Northwestern astrophysicist Claude-André Faucher-Giguère, lead author of the study, explains: “The discovery of these galaxies was a big surprise because they were significantly brighter under this condition.” In general, a galaxy is bright , because she is big. However, because these galaxies formed at the cosmic dawn, not much time has passed since the Big Bang. How could these massive galaxies come together so quickly? Our simulations show that galaxies have no problem forming this luminosity at the cosmic dawn. “.
The new simulations actually suggest that the James-Webb’s distant problem galaxies are smaller than we might imagine based on their luminosity, and that their masses are therefore smaller, consistent with the average size of galaxies predicted by previous models .
Better consideration of star formation processes through algorithms leads to very intense eruptions of new stars, separated by quiet phases. These bursts are more violent and produce more stars than those we knew before, and the result is that small galaxies can appear just as luminous as large galaxies at the start of reionization, naively leading us to believe that galaxies are growing faster.
Ultimately, the researchers appear to reproduce the James Webb observations and agree with the Standard Cosmological Model. Therefore, if this is indeed the case, we have no further reason to doubt this model or give further credence to the lunar theory.
The new simulations were carried out as part of the Feedback of Relativistic Environments (FIRE) project, founded by Faucher-Giguère along with collaborators from the California Institute of Technology, Princeton University and the University of California at San Diego. The new study involves employees from the Center for Computational Astrophysics at the Flatiron Institute, the Massachusetts Institute of Technology and the University of California, Davis.
The Northwestern University press release states: “FIRE simulations combine theoretical astrophysics and advanced algorithms to model galaxy formation. The models allow researchers to study how galaxies form, grow and change shape, taking into account the energy, mass and fluxes of chemical elements sent by stars.
A few years ago, FIRE proposed an elegant solution to a problem in the Standard Cosmological Model that appeared unable to explain the small number of dwarf galaxies observed around large galaxies such as the Milky Way.