Peering Back in Time: JWST Discovers Giant Protocluster in the Early Universe

Images of a proto-cluster of seven galaxies that were released by NASA on Monday provide insight into the early universe’s creation. The galaxy collection is anticipated to expand in size and mass, imitating the Coma Cluster, one of the universe’s densest known clusters of galaxies.

Understanding how the first galaxies and galaxy clusters evolved in the early cosmos is one of the main objectives of the James Webb Space Telescope (JWST), and the new pictures sent our way by JWST show us just how useful it is. The seven galaxies revealed in the latest JWST images are the first to be spectroscopically confirmed as part of a developing galaxy cluster, according to researchers.

When were these galaxies formed?

These seven galaxies have been proven to be gravitationally tied together, and astronomers believe they will eventually create a much larger galaxy cluster. The seven galaxies were discovered only 650 million years after the Big Bang, and Hubble recognized them as good candidates for further investigation by JWST.

Massive clouds of gas collapse and spin to form galaxies. Stars develop within them as they evolve. Whole galaxies can collide and change their appearance. We may glimpse galaxies at early phases of their life and learn more about their evolution by looking far into space. They are more numerous, have odd forms, and have intense outbursts. Galaxies may be traced back more than 10 billion years.

We know dark matter must be present in galaxies due to its influence on rotation rates, and it is probable that it had a role in galaxies’ creation. However, unlike the top-down theory, the bottom-up theory does not assume that the original proto-galaxies were the same size as present-day galaxies. Instead, it holds that they were considerably smaller at first, and that it was only later that they developed to their current size by means of repeated mergers.

Astronomers are quite certain that mergers had a part in the formation of the galaxies we see nowadays. One explanation for this is that powerful observatories such as Hubble have uncovered countless examples of galaxy mergers that are currently happening now. 

Furthermore, the most distant galaxies, which are viewed as they were billions of years ago due to the limiting speed at which light travels, seem far smaller and less well-structured than nearer ones, according to NASA’s JWST. This appears to be a convincing sign that galaxies developed between their original creation and now.

How did astronomers figure out the distance between these galaxies? 

Redshift is used by astronomers to calculate approximate distances to very distant galaxies. The more distant an object is, the more redshifted it will be. As the universe expands, light wavelengths are stretched and “shifted” to longer, redder wavelengths. Very distant objects may release energy in ultraviolet or even higher energy wavelengths, but shorter wavelengths, such as ultraviolet and X-ray, are closer to the blue end of the electromagnetic spectrum.

Therefore, in the early universe, extreme distances were defined by how much the light emitted by an object had shifted as it travelled through space. These galaxies have a redshift of around 7.9, which roughly equates to about 650 million years after the Big Bang.

Which is the earliest galaxy observed by JWST?

One of the earliest galaxies observed by the James Webb Space Telescope is JADES-GS-z13-0, which is estimated to have been imaged 325 million years after the Big Bang occurred. 

The Near-Infrared Spectrograph (NIRSpec) instrument on the JWST helped astronomers precisely measure the distances between these galaxies and hence establish their ages, as well as determining that the galaxies are part of a growing cluster.

How does the JWST help astronomers?

Based on imaging data alone, one galaxy, YD4, was originally predicted to be at a greater distance and was not thought to be part of this group of galaxies, but the new data provided by JWST helped the astronomers determine that YD4’s redshift is the same as the other galaxies in the cluster.

The European Space Agency claimed that before the existence of JWST, they did not have these high-resolution images and special infrared data to do this type of research on these clusters of galaxies.

Role of the Hubble Space Telescope in discovery

The Hubble Space Telescope identified these galaxies as candidates for observations by JWST for future research, as it has done countless times before.

The HST Frontier Fields program was used to make detailed measurements of very distant galaxies using gravitational lensing. However, because Hubble cannot detect light beyond the near-infrared, it can only see so much detail. JWST then became operational, allowing scientists to view further and deeper, collecting thorough spectroscopic data as well as pictures.

The Future of the James Webb Space Telescope

These kinds of findings will be made possible during the next ten years by the Nancy Grace Roman Space Telescope, a future observatory that NASA plans to launch in early 2027. It will make it easier to identify galaxy clusters in the early universe like the one found in this study because of its wide-area survey capabilities, which will be more than 100 times greater than those of JWST.

The study, which was published in the Astrophysical Journal Letters, was led by Takahiro Morishita of IPAC-California Institute of Technology. “This is a very special, unique site of accelerated galaxy evolution, and Webb gave us the unprecedented ability to measure the velocities of these seven galaxies and confidently confirm that they are bound together in a protocluster,” he said.

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