GN-z11 is still an ultra-distant galaxy, but it’s not even in the top 10 anymore for most distant galaxy.
Hundreds of times as many luminous, early galaxies were found as were initially expected, and a new record holder, MoM-z14, was just announced on May 16, 2025.
Nevertheless, within this field-of-view, an enormous number of ultra-distant galaxy candidates have been identified.
The most common “type” of ultra-distant galaxy found by JWST is illustrated above: what we know as “little red dot” galaxies.
With these four contributions, all combined, the Universe finally makes sense, even with the abundant presence of these ultra-distant JWST galaxies.
Regardless of our level of understanding, there is always more to learn about the universe. Astronomy is the study of the universe as we see it, after all, and as we develop better instruments and telescopes, we will inevitably discover details, objects, and even phenomena that were previously unobservable with the aid of earlier generations’ instruments. In many ways, we only started to comprehend the appearance of the universe with the development of space telescope technology, such as NASA’s Hubble Space Telescope. The James Webb Space Telescope (JWST) is pushing us past all of Hubble’s previous boundaries in the 2020s, finding objects in the Universe that are younger, fainter, farther away, and more primitive than ever before.
The Hubble Space Telescope had found GN-z11, the only confirmed galaxy from the first 500 million years of cosmic history, back in 2022, before JWST started science operations. Though they were only that—candidates—there were a number of other ultra-distant galaxy candidates. To find more and verify or disprove the ones we already had, a better tool like JWST would be required.
Fast-forward to the present, in 2025. Though it is no longer among the top 10 most distant galaxies, GN-z11 is still an ultra-distant galaxy. There were hundreds of times as many bright, early galaxies discovered as were first anticipated, and on May 16, 2025, MoM-z14 was just revealed as the new record holder. Here are the findings, their implications, and the unanswered questions.
This is the Cosmic Evolution Survey, or COSMOS survey, which is the largest deep survey of the universe ever carried out. This field’s full-resolution version measures more than 10 gigapixels, or more than 100,000 pixels on each side, and is made up of an astounding 575 distinct adjacent, overlapping Hubble images that required almost 1000 hours of total observation time. Furthermore, the sky is so big that it would take more than 20,000 COSMOS surveys to cover it all if we wanted to.
However, there are a vast number of ultra-distant galaxy candidates within this field of view. A new observatory is needed to measure the light from the most distant galaxies because they experience such extreme redshifts, or stretching effects, due to the expansion of the Universe, even though the closer galaxies can be spectroscopically confirmed from the ground using instruments like the Very Large Telescope, the Magellan telescope, the Subaru telescope, the Canada-France-Hawaii telescope, or the Suzuki telescope.
The most potent infrared space telescope ever built by humans, JWST, is perfectly suited to this mission. Before the JWST science era even started to take into account galaxies in the COSMOS field, it had already found and verified a vast number of bright, ultra-distant galaxies in the Universe. In fact, there are about 100 times as many of these galaxies as we had anticipated.
The above illustration shows the most prevalent “type” of ultra-distant galaxy discovered by JWST: “little red .” galaxies. When we initially started finding them, which was almost instantly, many people made the hasty assumption that cosmology was flawed and that we had no idea how galaxies formed or developed. However, as additional research and data came in, four tentative explanations for what JWST was observing surfaced.
overperformance in optics. The fact that JWST was collecting more light (and was kept cleaner during construction) than we had anticipated contributed to the galaxies being brighter and more numerous than we had anticipated.
limitations of the simulation. Without concentrating on the rarest but most severe small-scale overdensities, the majority of simulations were run at medium resolution. It is anticipated that simulations will include more bright, early galaxies when these “rarepeak” regions are included.
exploding star formation. A steady, maximum rate of star-formation that accumulates over time is the foundation of the majority of galaxy models. However, real galaxies frequently surpass those rates momentarily, producing stars in massive (but short) explosions that momentarily increase their brightness. The brightest ones are then the ones we prefer to notice at that moment.
Improvements to AGN. It is predicted that the centers of almost all galaxies, including early-type galaxies, contain supermassive black holes, many of which are either actively or recently active. As a result, AGN activity artificially (but momentarily) inflates the observed brightnesses of many of these tiny red . galaxies.
Despite the abundant presence of these ultra-distant JWST galaxies, the Universe finally makes sense when these four contributions are joined.
Prior to this, numerous galaxies were found by JWST collaborations like CEERS (the Cosmic Evolution Early Release Science Survey), GLASS, UNCOVER (the Ultradeep NIRSpec and NIRCam Observations before the Epoch of Reionization), and JADES (the JWST Advanced Deep Extragalactic Survey), all of which surpassed the previously held record of GN-z11. The following galaxies were among these far-off ones.
bright emission lines of hydrogen in galaxies.
enormous “red monster” galaxies.
the baby galaxy cluster that is the furthest away.
Only about 300 million years after the Big Bang, a new, oxygen-rich record-setter first appeared.
in addition to numerous other discoveries that are fundamentally altering our understanding of how the universe evolved.
The latest discovery, galaxy MoM-z14, is now ready to be added to the story. As of May 16, 2025, it is the most distant galaxy currently known to humanity, surpassing JADES-GS-z14-0. At a range of near-infrared wavelengths, it was first imaged photometrically, just like the majority of the ultra-distant JWST galaxies found.
zero to nine microns.
One to fifteen microns.
1 to 50 microns.
2:00 microns.
2.77 microns.
3point 56 microns.
as well as 4point 44 micron.
The early presence of neutral hydrogen in the Universe causes all light with wavelengths shorter than ~121 nanometers (where the Lyman-α emission/absorption transition takes place) to be absorbed. The expansion of the Universe then causes the light to be stretched. This indicates that the object is visible through the last four filters, while the first three filters show no light at all.
In order to determine the actual distance to the galaxy, we must conduct a process known as a spectroscopic follow-up, in which we dissect the light from the object into its constituent wavelengths. Even a galaxy this distant will show emission lines from the nearby ionized atoms thanks to the amazing spectroscopic power of JWST’s NIRSpec instrument. A combination of factors is to blame for this.
In addition to the primordial signs of hydrogen and helium, this galaxy contains heavy elements like nitrogen, carbon, and oxygen because it has already produced previous generations of stars.
This galaxy must be actively forming stars either now or very recently in order to be seen from such a great distance. This suggests that there are a lot of ultraviolet photons in the galaxy, which can remove one or more electrons from the atoms within.
The electrons emit “lines” at a distinctive set of frequencies and wavelengths as they recombine with their ionized nuclei, cascading down a range of atomic energy levels.
And each of those lines, if they can be resolved by our instruments, will show the redshift (z) of a galaxy because the wavelengths of those lines will be observed at the rest-frame wavelength multiplied by “1+redshift” (or 1+z).
We can conclusively determine that this object is at a redshift of z = 14.44, setting a new cosmic record, because we have observed emission lines from nitrogen, carbon, helium, and oxygen in various ionization states in addition to the Lyman break feature, which corresponds to the Lyman-α wavelength.
A redshift of z = 14.44 indicates that light with a wavelength that was initially emitted from this object will be observed by us on Earth (or in space with JWST) with a wavelength that is 15.44 times greater. At 121 point 5 nanometers, the Lyman-α line was first detected as ultraviolet light. However, the expansion of the universe causes that light to be stretched over a period of more than 13½5 billion years. It passes through the ultraviolet (which ends at about 400 nm), visible light (400–700 nm), and infrared (until it finally starts to appear at a new wavelength of 1½88 microns).
This translates into an estimated 282 million-year age for the universe, which is only 2 percent of its present age. This object is currently 33.8 billion light-years away from us, making it the most distant object ever discovered in the Universe. This distance translates to a light-travel time of roughly 13.53 billion years.
Because we know how the Universe expands, we can also deduce other characteristics about this galaxy, such as its size (it has a diameter of about 500 light-years), compactness (its light is very concentrated and not diffuse or extended), and surprisingly low dust content (because of the light’s steep ultraviolet slope).
The fact that it is “dust-free” is already a very intriguing characteristic. Recall that we anticipated finding relatively few of these bright galaxies at such great distances prior to JWST’s initiation of ultra-distant Universe observations. JWST’s optical overperformance, enhanced simulations, bursty star formation, and AGN (active galactic nuclei) brightness enhancement were the four main explanations.
AGNs usually function by introducing energy into an accretion disk, which heats it up and makes it glow. This increases the galaxy’s overall brightness. However, doing so would result in a very shallow ultraviolet slope for its light and make the galaxy appear to be quite extended in space—neither of which accurately describes the galaxy’s light that we are currently seeing.
This suggests that not only is an AGN not the primary light source for this object, but that the central supermassive black hole may be the source of very little light. Indeed, a number of the early “little red .” galaxies discovered by JWST appear to show little to no evidence of AGN activity, especially the smaller, more compact ones. One would expect, if not demand, that there would be compelling evidence of a recent or ongoing bursty star-formation episode within this galaxy if there is no AGN activity present.
And the evidence certainly supports that. It appears that during the last 10 million years or less, the star-formation rate increased dramatically by a factor of 10 or more, and it has stayed at this high level for the last three to four million years at the very least. This also clarifies the reason.
For example, doubly ionized carbon emission lines have such large (about 15 Å) equivalent widths (an astronomical term for the amount of continuum intensity required to make up the total intensity of an observed emission line).
Due to the extremely high degree of ionization, many atomic species have double or triple ionization states.
The inferred gas density is extremely high, about twenty times higher than that of the gas-depleted former distance record-holder, JADES-GS-z14-0.
and the reason that, compared to other (even larger) galaxies discovered at such great distances, the galaxy emits a greater amount of energy in the form of triply-ionized nitrogen.
We can confidently conclude that the majority of the light we are seeing from this galaxy was from stars that formed relatively recently in its cosmic history: within the last 10 million years or so. However, we are unable to determine with current observations whether a population of older stars exists alongside these newly-forming ones, though future NIRSpec and/or ALMA observations may be able to help.
The unexpectedly high abundance of these extremely bright, extremely distant galaxies is the big puzzle—or, to put it another way, the big “reveal”—that JWST has given us about the early Universe. Even though we believe we can explain them now that they have been found, it’s crucial to acknowledge that our initial estimates of how frequently we should find them were drastically off by a factor of 100 or even 200. The discovery of MoM-z14, a new galaxy, provides strong confirmation of this image. Furthermore, some fresh queries are brought up.
The unique characteristics of this far-off galaxy’s light suggest that there isn’t much neutral gas in it. But the Universe shouldn’t be completely reionized until about 550 million years after the Big Bang, while MoM-z14 arrived from a period when the Universe was only about half that old. How come this area has so little neutral gas at such an early stage? Could it be that the intergalactic medium surrounding this object underwent a complete ionization process hundreds of millions of years before it did elsewhere?
Furthermore, even most of the JWST-inspired models struggle to explain the presence of MoM-z14 and JADES-GS-z14-0 at such great distances and early times, unless there is something exotic occurring at very early times, such as an unexpected evolution in star-formation efficiency or the presence of some exotic form of energy (like evolving dark matter or early dark energy).
It is important to note that the reason this galaxy is called MoM-z14 is not because it is “the mother of all galaxies” and should be shortened to MoM. Rather, the discovery paper for this galaxy is the first outcome of the “Mirage or Miracle” survey, which was created to spectroscopically test the nature and abundance of luminous galaxies (and luminous galaxy candidates) from the first 500 million years of cosmic history. This galaxy is a (scientific) miracle according to the survey team’s definition since it has been established that it is not a mirage.
We can be sure that many of the early “little red .” galaxies that are out there will not show much evidence for large AGN contributions, but will instead be compact and dominated by a burst of recent star-formation, thanks to this discovery, which is likely the first of many ultra-distant galaxies that will be revealed by this survey and the larger-field COSMOS-Web survey. Galaxies GN-z11 and GLASS-z12 already exhibit this, but the discovery of MoM-z14 suggests that they might not be anomalies after all.
Lastly, even at this early age, this galaxy is fairly massive, weighing around 100 million solar masses, which is equivalent to the Small Magellanic Cloud. We can be sure that future observations of MoM-z14 and other galaxies that are certain to be found at similar, comparable distances will put us in a very favorable position to better understand how our Universe evolved to become the fascinating way it is today. Will this grow into a cosmic behemoth? Will it grow into a dwarf galaxy? Or does it represent one of the largest and most massive examples of an early globular cluster?
