The James Webb Telescope reveals an amazing diversity of primordial galaxies!

A new study looked at 850 galaxies dating back between 11 and 13 billion years ago. Using new images obtained by James Webb, they show a variety of galaxies not seen before.

Since arriving at the L2 Lagrangian point at the end of January 2022, the James Webb Space Telescope has continued to revolutionize our observations of the universe. This time it’s timeancient galaxies It focused, more accurately, on some of the first ones that inhabited the young universe. The results obtained are unprecedented compared to those obtained by Hubble. This is evidenced by a study accepted in the journal Astrophysical Journal and available at ArXiv. An international team of researchers used data collected by both James-Webb and Hubble and compared the results obtained.

In all, the team examined 850 galaxies with ” red shift between 3 and 9. This parameter, also denoted as “z”, represents the redshift of the observed star, and thus the speed with which it is moving away from us. According to the value of this displacement and find out the evolution of accelerationThe expansion of the universe, it is possible to deduce the distance of the star in question, and thus the period in which we are looking at it. Thus, the researchers went back in time between 11 and 13 billion years! Either at the dawn of the universe as we know it today.

Great variety of shapes

Those Primordial galaxies They are the ones that brought the first heavy elements into the universe. Stars formed there, died there, and if they were massive, they expelled large amounts of material at high speed when they died. “The overall density and rate of star formation in the universe increased until it peaked at z∼2−3, and then began to decline to the lower current levels”explains the study. This is what then allowed the formation of heavier and heavier elements, while initially only hydrogen and helium were present. And these galaxies, contrary to what the researchers believed, turned out to be much more diverse and mature than expected!

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To ensure this, the team chose to customize both of them galaxy According to different criteria, such as “Main galaxy morphology, interaction class, different quality and structure indicators”Study details. For major morphologies, they divided them as follows: discal, spherical, irregular/particular, point source/unresolved, or still unclassifiable. Each category can belong to several categories, as shown in the following figure.

In this image, only galaxies that can be classified as typical are shown. There are still irregular, which can correspond to A merger of several galaxies, or unclassified or unresolved ones. So there were already many different shapes of galaxies over 11 billion years ago! “There have been previous studies indicating that we see a lot of galaxies with high redshift disks, which is true, but in this study we also see a lot of galaxies with other structures, such as spheroids and irregular shapes, as we do at low redshifts.said Jeyhan S. Kartaltepe, first author of the study and researcher at Scientific Survey of Early Publication of Cosmic Evolution (CEERS). This means that even at these high redshifts, the galaxies would have already evolved and had a wide range of structures. »

A stark difference between Hubble and James Webb

The study also shows a striking difference between the galaxies he saw Hubble And the same thing James Webb recently noted: “Of the 850 galaxies used in the study and previously identified by Hubble, 488 have been reclassified to different configurations after being viewed in more detail using the JWST,” Bayan says Rochester Institute of Technology. It appears in passing that details are still missing. “This tells us that we don’t yet know when the first galactic structures formed.Jeyhan S. Kartaltepe reported. We don’t yet see the first disk galaxies. We would need to look at more galaxies at higher redshifts to determine when features like disks formed. »

Findings that will soon be backed up by new research, eg CEERS programme More than 60 hours of additional observation have already been accumulated since this study. It aims to identify the first galaxies, and thus to understand how they formed, when the universe was still only made up of hydrogen, helium and dark matter. With these new observations, potentially thousands more galaxies will be revealed to astrophysicists. In addition, James Webb’s first-selected COSMOS-Web program will provide a larger sample with more than 200 hours of near- and mid-infrared observations. Enough, this time, to get to know tens of thousands of galaxies!

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