NASA’s James Webb Space Telescope (JWST) has made an incredible discovery by identifying the oldest and most distant galaxy ever found. This exciting find helps scientists learn more about the early Universe.

The galaxy was discovered by a group of researchers working on the JWST Advanced Deep Extragalactic Survey (JADES) project. They found it near a famous area in the sky called the Hubble Deep Field, where many other distant galaxies have been seen.

These galaxies help us understand the stars and the unique chemical makeup of the early Universe, said Dr. Francesco D’Eugenio from the University of Cambridge, one of the researchers.

The Universe is expanding, which means that light from distant galaxies gets stretched out and changes color, a process known as redshift. In this case, the light from the newly discovered galaxy has been stretched 15 times longer, moving it from ultraviolet light (which we can’t see) to infrared light (which we also can’t see without special equipment like JWST).

Scientists believe galaxies form in areas where gravity pulls gas and dark matter into dense clumps called ‘halos’. These halos merged quickly in the early Universe, forming larger collections of matter. Finding these early galaxies is important because it helps scientists understand how galaxies like our Milky Way formed and evolved over time.

Scientists used the NIRSpec (Near-Infrared Spectrograph) spectrograph on NASA's James Webb Space Telescope to obtain a spectrum of the distant galaxy JADES-GS-z14-0 to accurately measure its redshift and thus determine its age. The redshift can be determined from the location of a critical wavelength known as the Lyman-alpha break. This galaxy dates back less than 300 million years after the Big Bang.
Scientists used the NIRSpec (Near-Infrared Spectrograph) spectrograph on NASA’s James Webb Space Telescope to obtain a spectrum of the distant galaxy JADES-GS-z14-0 to accurately measure its redshift and thus determine its age. The redshift can be determined from the location of a critical wavelength known as the Lyman-alpha break. This galaxy dates back less than 300 million years after the Big Bang. Credit: Joseph Olmsted (STScI) / NASA, ESA, CSA

The two galaxies discovered have been given the names JADES-GS-z14-0 and JADES-GS-z14-1. JADES-GS-z14-0 is the more distant of the two and stands out for its size and brightness. JWST measured this galaxy to be over 1,600 light-years in diameter. Unlike other bright galaxies that shine because of supermassive black holes, JADES-GS-z14-0’s light comes from young stars.

The combination of high luminosity and stellar origin makes JADES-GS-z14-0 the most distinctive evidence yet of the rapid formation of large, massive galaxies in the early Universe. This finding challenges previous ideas about how quickly galaxies could form and grow in the early Universe. Early images from JWST hinted at the existence of such vigorous early galaxies, and this find confirms those hints.

JADES-GS-z14-0 is now the archetype of this phenomenon, said Dr. Stefano Carniani from the Scuola Normale Superiore in Pisa, lead author of the discovery paper. It’s astonishing that the Universe could create such a galaxy in just 300 million years.

At first, the researchers were puzzled when they saw JADES-GS-z14-0 over a year ago because it appeared close to another galaxy, making it hard to tell if it was truly distant. However, in October 2023, they took even deeper images, spending five days observing the same spot with JWST’s Near Infrared Camera. They used special filters to better identify early galaxies, and their confidence grew that JADES-GS-z14-0 was indeed very far away.

We couldn’t find any plausible way to explain this galaxy as merely a neighbor of the closer galaxy, said Dr. Kevin Hainline from the University of Arizona.

The team also used JWST’s Mid-Infrared Instrument to take even more detailed images. The galaxy was bright enough to be detected at a wavelength of 7.7 microns, which confirmed its distance.

We are seeing extra emission from hydrogen atoms and possibly even oxygen, common in star-forming galaxies, but here shifted to unprecedented wavelengths, said Jakob Helton from the University of Arizona.

The researchers decided to include this galaxy in a major 75-hour observation campaign to study early galaxies. The results confirmed that JADES-GS-z14-0 is indeed a record-breaking galaxy, with JADES-GS-z14-1 being almost as distant.

Beyond just measuring the distance, the detailed study of these galaxies will help scientists learn more about their characteristics. Since JADES-GS-z14-0 is relatively bright, it provides a great opportunity for in-depth analysis.

We could have detected this galaxy even if it were ten times fainter, meaning we might find even earlier examples, said Brant Robertson from the University of California, Santa Cruz. The early Universe has much more to reveal.


Sources

University of Cambridge | Stefano Carniani, Kevin Hainline, et al., A shining cosmic dawn: spectroscopic confirmation of two luminous galaxies at z∼14, arXiv:2405.18485. arxiv.org/abs/2405.18485 | Jakob M. Helton, George H. Rieke, et al., JWST/MIRI photometric detection at 7.7 μm of the stellar continuum and nebular emission in a galaxy at z>14, arXiv:2405.18462. arxiv.org/abs/2405.18462 | Brant Robertson et al., Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic Star-Formation Rate Density 300 Myr after the Big Bang, arXiv (2023). DOI: 10.48550/arxiv.2312.10033


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