Impossible Galaxies – Early Galaxies discovered by JWST

The James Webb Space Telescope (JWST) has captured some fascinating observations on early galaxies which are dubbed as Impossible Galaxies. These Galaxies challenge our current understanding of galaxy formation and have been dubbed “impossible galaxies” because their properties seem to contradict established cosmological theories.

The James Webb Space Telescope (JWST)’s infrared capabilities allow it to peer further back in time than any previous telescope. This has enabled it to detect galaxies that existed just a few hundred million years after the Big Bang.

NASA‘s James Webb Space Telescope (JWST) has discovered 6 impossible galaxies so far. ZF-UDS-7329 is one of them.

ZF-UDS-7329 Impossible Galaxy:

The galaxy, known as ZF-UDS-7329, was formed some 13 billion years ago, but up until now, earth-based technology has not allowed astronomers to locate it. With the successful launch of the James Webb Space Telescope (JWST) in 2021, the team was able to examine the galaxy more closely and obtain a better understanding of it.

A multinational research team led by Distinguished Professor Karl Glazebrook of Swinburne University of Technology in Melbourne examined ZF-UDS-7329.

It is a “Quiescent Galaxy,” meaning that at the time of observation, there was little to no star production. The galaxy has more than four times the mass of the stars in our galaxy, although being only a small portion of the Milky Way’s size at 2 kiloparsecs, or 6,530 light-years, across.

The study’s findings have the potential to “completely upend our understanding of the nature of dark matter and how galaxies form.”

A “new opening” for our understanding of dark matter may result from this research, and the discovery of more objects similar to ZF-UDS-7329 might “really upset our ideas of galaxy formation.”

Impossible Galaxies’ Unexpected Maturity:

These early galaxies appear to be surprisingly massive and well-developed, containing many more stars than expected for their age. Current models suggest galaxies should take much longer to form such large stellar populations.

Some of these “impossible galaxies” seem to be undergoing incredibly rapid star formation rates. This rapid growth challenges our understanding of how galaxies evolved in the early universe.

Theoretically, these galaxies shouldn’t exist since they were so bright. Massive galaxies with a star count comparable to the Milky Way should only be able to produce brightnesses of this magnitude, yet these early galaxies formed far faster than our own.

The revelation posed a threat to the conventional understanding of cosmology and even the concept of galaxy formation among physicists.

A galaxy is usually bright because it is large. However, not enough time has elapsed since the Big Bang since these galaxies formed during cosmic dawn. How could these huge galaxies assemble so quickly?

Although cosmologists have previously calculated that the process started slowly taking shape during the first few hundred million years after the Big Bang, scientists are unsure of the precise time when the first star clusters began to combine into the beginnings of the galaxies we see today.

This illustration shows a messy, chaotic galaxy undergoing bursts of star formation. This star formation is intense. It was known that it affects its host galaxy, but this new research shows it has an even greater effect than first thought. The winds created by these star formation processes stream out of the galaxy, ionizing gas at distances of up to 650,000 light-years from the galactic center.

Possible Explanations:

While these observations are exciting, scientists are still working on explanations. Here are a few possibilities:

Incomplete Understanding:

Our current models of galaxy formation might be incomplete. New data from JWST could lead to revisions in these models to account for more rapid early growth.

Environmental Factors:

Perhaps the environment surrounding these galaxies played a crucial role in their accelerated development. Dense pockets of gas and dust could have fueled rapid star formation.

Selection Bias:

Given the vastness of the universe, JWST might be preferentially observing rare, atypical galaxies due to their brightness. Future observations may reveal a more diverse population of early galaxies.

Ongoing Investigation:

The findings from JWST are just the beginning. Astronomers are using the telescope to gather more data on these “impossible galaxies” and others like them. This will help us refine our understanding of galaxy formation in the early universe and potentially rewrite our cosmic story.

Astrophysicists’ Simulations about Impossible Galaxies:

According to widely accepted hypotheses, these early protogalaxies reached adolescence between one and two billion years into the universe’s existence, creating dwarf galaxies that started consuming one another to become larger ones similar to our own.

Astronomers were therefore taken aback when the JWST discovered millions of exceptionally bright early galaxies, some of which even resembled our own. It was a finding that severely questioned their most fundamental theories about how the universe came to be.

These galaxies would need to have swollen to huge sizes in a fraction of the ordinary period if they were similar to our own in order to light so brightly.

The researchers built a model of galaxy formation and ran it through a supercomputer to simulate the swirling, clotting gas of the early universe as it converted into stars, which in turn developed into galaxies, in order to look into what may have given these galaxies their strange sparkle.

The scientists discovered that stars may have formed in sudden bursts following years of quiescence by closely examining the mass, energy, momentum, and chemical makeup of the early cosmos.

This phenomenon, called “bursty star formation,” differs from the current universe’s constant pace of star creation and may account for the early universe’s extreme brightness.

When stars in the early universe were created, they sucked in gas and then expelled it again when they died in a phenomenon known as supernovas.

After millions of years of dormancy, stars were able to develop in quick, dazzling bursts because of this pulsating pulse of gas. Eventually, as the universe became older and galaxies became larger, their gravitational pull became too great for gas to be expelled by supernovas, which made star formation occur more slowly.

The JWST-detected galaxies appear brighter because we are witnessing their stars develop in these abrupt bursts, not because they have more stars than the current galaxy population if the bursty star formation theory is valid.

The most massive stars in a galaxy produce most of the galaxy’s light, according to Faucher-Giguère. “More massive stars have shorter lives because they burn faster. In nuclear reactions, they deplete their fuel very quickly.

Therefore, a galaxy’s brightness has a stronger correlation with the number of stars that have formed during the previous few million years than it does with the galaxy’s total mass.”

Remarkably, our mainstream model of the universe will have survived if astrophysicists’ calculations are accurate. However, before they can be certain, scientists will need to conduct more accurate measurements of the enigmatic galaxies at cosmic dawn.


The “impossible galaxies” are a fascinating example of how JWST is revolutionizing our understanding of the universe. As more data is collected and analyzed, we can expect to solve the mysteries surrounding these objects and gain a clearer picture of galaxy formation in the early universe.

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