5 big lessons from JWST’s new record-setting galaxy

Everywhere we look, our Universe is full of luminous matter.

The ‘red-and-dead’ galaxy NGC 1277 is found inside the Perseus cluster. While the other galaxies contain a mix of red-and-blue stars, this galaxy hasn’t formed new stars in approximately 10 billion years. Foreground, closer objects, like stars, as well as more distant galaxies, are all ubiquitous throughout this image.

Galaxies, powered by stars, exist strewn throughout the cosmos.

The galaxies that compose Pandora’s Cluster, Abell 2744, are present within the three separate cluster components easily visually identifiable, while the remaining background sources are scattered all throughout the Universe, including many from the first ~1 billion years of cosmic history. This field of view is now known to contain many of the earliest galaxies ever found, as well as the youngest proto-cluster of galaxies ever discovered to date: just 650 million years after the Big Bang.

Farther away, they are bluer, smaller, and less evolved.

Galaxies comparable to the present-day Milky Way are numerous, but younger galaxies that are Milky Way-like are inherently smaller, bluer, and richer in gas in general than the galaxies we see today. Fewer galaxies have disks and spiral shapes as we look farther back in time. Over time, many smaller galaxies become gravitationally bound together, resulting in mergers, but also in groups and clusters containing large numbers of galaxies overall.

Even at our instruments’ limits, galaxies still abound.

This tiny fraction of the JADES survey area, taken with JWST’s NIRCam instrument, showcases relatively nearby galaxies in detail, galaxies at intermediate distances that appear grouped together, and even ultra-distant galaxies that may be interacting or forming stars, despite their faint nature and red appearance. Even though we’ve been performing JWST science for over two years, we are only beginning to probe the full richness of the cosmos with JWST.

No deeper view exists than JADES: the JWST Advanced Deep Extragalactic Survey.

This image shows the region of study of the JWST Advanced Deep Extragalactic Survey (JADES). This area includes and contains the Hubble eXtreme Deep Field and reveals new galaxies at record-breaking distances that Hubble could not see. The colors on JWST images are not “true color” but rather are assigned based on a variety of choices. This image, released in December of 2022, has since been augmented by follow-on observations within the same region of space, with spectroscopic observations required to determine the distance to these galaxies.

With new spectroscopic data, the cosmic distance record has fallen again.

This image shows the spectrum, or intensity as a function of wavelength, of the distant galaxy JADES-GS-z14-0 as acquired with JWST’s NIRSpec instrument. The Lyman break feature tells us that the galaxy is at a redshift of z=14.32, corresponding to an age of the Universe at that time of just 285 million years.

JADES-GS-z14-0 is now the most distant galaxy ever found: just 285 million years after the Big Bang.

If you plot the cosmic distance record over time, it’s clear that there were many big jumps: in the 1960s, in the late 1990s, and now again in the 2020s in the JWST era. Although there are still uncertainties in cosmology, this new record-breaking galaxy, JADES-GS-z14-0, must appear between 270 and 305 million years after the Big Bang, corresponding to a redshift of z = 14.3.

Here are the 5 big lessons we’ve already learned from its discovery.

Shown within the context of the JWST JADES field, galaxy JADEs-GS-z14-0 is completely unremarkable, but nevertheless has just broken the cosmic distance record again, becoming the first galaxy ever found when the Universe was under 300 million years old: just 2.1% of its current age. From its vantage point within the expanding Universe, it would see our proto-Milky Way as it was some 13.52 billion years ago: when we were just 2.1% of our current age.

1.) Not all early galaxies are compact.

Among the most distant galaxies, GN-z11 and GHZ2 are among the brightest, and yet are still remarkably compact. JADES-GS-z14-1 is more typical: fainter but still very compact, while JADES-GS-z14-0 is more puzzling: bright and extended, suggesting a physical size of ~1700 light-years at its incredible distance.

Although (second place) JADES-GS-z14-1 is point-like, its more distant sibling already spans 1,700 light-years across.

The galaxy JADES-GS-z14-0, alongside an interloping, much closer unrelated galaxy that happens to be along the exact same line-of-sight. Its extended nature is clearly visible even in this blown-up NIRCam image of the two galaxies.

2.) Not all ultra-distant galaxy candidates are correct.

Before JWST, there were about 40 ultra-distant galaxy candidates known, primarily via Hubble’s observations. Early JWST results revealed many more ultra-distant galaxy candidates, but now a whopping 717 of them have been found in just the JADES 125 square-arcminute field-of-view. The entire night sky is more than 1 million times grander in scale. While some candidates will survive spectroscopic follow-up, others will not. Much science remains to be conducted.

Some possible ultra-distant galaxies are simply dusty and intrinsically red, spectroscopy reveals.

While JADES-GS-z14-0 and JADES-GS-z14-1 (in red) have turned out to be real, ultra-distant galaxies, many of the galaxy candidates (in blue) will turn out to be impostors at smaller distances from us: just intrinsically red and/or dusty. The blue dot with a black circle around it was also examined by NIRSpec, was unable to have its redshift confirmed based on the data acquired.

3.) Some galaxies are “hidden” by closer interlopers.

JADES-GS-z14-0, in the top inset box, is found behind (and just to the right of) a closer, brighter, bluer galaxy. It was only through the power of spectroscopy with incredible resolution, capable of separating the two sources, that the nature of this record-breakingly distant object could be determined. Its light comes to us from when the Universe was only 285-290 million years old: just 2.1% of its current age. JADES-GS-z14-1, just below it, comes from when the Universe was ~300 million years old. Compared to large, modern-day galaxies, all early galaxies contain a paucity of stars and have irregular, ill-defined shapes.

JADES-GS-z14-0 was only found by disentangling this galaxy from a closer one along the same line-of-sight.

The highly advanced NIRSpec instrument aboard JWST can take the light from a very tiny region of space. By pointing the telescope correctly, the desired sources, JADES-GS-z14-0 and JADES-GS-z14-1 in this case, can be acquired separately from even extremely nearby, partially overlapping sources. The key “Lyman-break” feature is easily observable in the spectrum of both galaxies, whereas photometric data shows nothing at filters of 1.5 microns or less, but plenty in filters of 2.0 microns or greater.

4.) This new record-holder is remarkably, unexpectedly bright.

By superimposing the spectra of the three most distant galaxies ever discovered on the same graph, JADES-GS-z13-0 (the former record holder), JADES-GS-z14-0 (the current record holder), and JADES-GS-z14-1 (newly discovered along with JADES-GS-z14-0), we can compare the brightnesses of these three galaxies. The most distant one is also the brightest by a factor of 4 or 5, posing a puzzle for astronomers. The Lyman break feature, where light goes from copious (at longer wavelengths) to non-existent (at shorter wavelengths) is indicated by the vertical lines.

Five times brighter than the prior (JADES-GS-z13-0) record-holder, JADES-GS-z14-0 is even shockingly visible to MIRI’s eyes.

This four-panel spread shows four different views of galaxy JADES-GS-z14-0 with photometric MIRI data. The fact that this galaxy has so much emission at 7.7 microns suggests that neutral, heated hydrogen (Balmer beta) and doubly ionized oxygen are both present in great abundances.

5.) But this galaxy is extremely dust-poor.

Whereas galaxies found at later times typically exhibit large amounts of dust, consistent with theories of dust production from supernova events, these two new record-breaking galaxies show evidence for dust produced only through AGB stars, not through supernova. This is a mysterious surprise in the new data, as the MIRI data, and the presence of doubly ionized oxygen, suggest a supernova-rich past.

The lack of dust inside JADES-GS-z14-0 presents a novel puzzle.

The central region of supernova remnant SN 1987A, as seen for the first time by JWST’s NIRCam instrument in 2023. The gaseous and dusty features in the interior of the remnant have been revealed in greater detail by JWST than any observatory previous, as core-collapse supernovae are incredible sites for the production of cosmic dust.

With JWST, our Universe’s past continues to come into focus.

Even from this zoomed-in view of the JADES field, it’s very difficult to pick out the most distant galaxy ever found, JADES-GS-z14-0, by eye. This animation shows its location with a green circle: overlapping with a brighter, bluer, closer galaxy.

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