Watch the video above to learn more about the most distant galaxy discovered so far.
NASA published this original article on May 30, 2024. Edits by EarthSky.
Most distant galaxy yet known
Over the last two years, astronomers have been using NASA’s James Webb Space Telescope (also called Webb or JWST) to explore what they call the Cosmic Dawn. It’s the first few hundred million years after the Big Bang, when the first stars and galaxies were born. Looking far out into space and far back in time with Webb, astronomers are using these galaxies to obtain vital insights into the ways in which the gas, stars and black holes were changing when the universe was very young. On May 30, 20224, these astronomers announced the most distant galaxy known so far.
These astronomers from around the globe used Webb to observe galaxies as part of the JWST Advanced Deep Extragalactic Survey (JADES) program. Using Webb’s Near-Infrared Spectrograph (NIRSpec), they obtained a spectrum of a record-breaking galaxy observed only 290 million years after the Big Bang. This corresponds to a redshift of about 14.
Redshift is a measurement of how much the expansion of the universe stretches a galaxy’s light. NASA invited Stefano Carniani from Scuola Normale Superiore in Pisa, Italy, and Kevin Hainline from the University of Arizona in Tucson, Arizona, to tell us more about how Webb found this source and what its unique properties tell us about galaxy formation.
Keep reading to learn what they said.
Finding the high redshift galaxy
Carniani and Hainline said:
Engineers designed the instruments on Webb to find and understand the earliest galaxies. And in the first year of observations as part of the JWST Advanced Deep Extragalactic Survey (JADES), we found many hundreds of candidate galaxies from the first 650 million years after the Big Bang.
In early 2023, we discovered a galaxy in our data that had strong evidence of being above a redshift of 14, which was very exciting. But there were some properties of the source that made us wary. The source was surprisingly bright, which we wouldn’t expect for such a distant galaxy. And it was very close to another galaxy such that the two appeared to be part of one larger object.
We observed the source again in October 2023 as part of the JADES Origins Field. New imaging data obtained with Webb’s narrower Near-Infrared Camera (NIRCam) filters pointed even more toward the high-redshift hypothesis. We knew we needed a spectrum, as whatever we would learn would be of immense scientific importance, either as a new milestone in Webb’s investigation of the early universe or as a confounding oddball of a middle-aged galaxy.
New most distant galaxy record
Carniani and Hainline continued:
In January 2024, NIRSpec observed this galaxy, JADES-GS-z14-0, for almost 10 hours. And when astronomers first processed the spectrum, there was unambiguous evidence that the galaxy was indeed at a redshift of 14.32. This shattered the previous most-distant galaxy record (z = 13.2 of JADES-GS-z13-0).
Seeing this spectrum was incredibly exciting for the whole team, given the mystery surrounding the source. This discovery was not just a new distance record for our team; the most important aspect of JADES-GS-z14-0 was that at this distance, we know that this galaxy must be intrinsically very luminous. From the images, the source is more than 1,600 light-years across. So that proves the light we see comes mostly from young stars and not from emission near a growing supermassive black hole. This much starlight implies the galaxy is several hundreds of millions of times the mass of the sun!
This raises the question: How can nature make such a bright, massive and large galaxy in less than 300 million years?
Most distant galaxy is surprisingly bright
Carniani and Hainline also said:
The data reveal other important aspects of this astonishing galaxy. We see the color of the galaxy is not as blue as it could be, indicating some of the light is reddened by dust, even at these very early times.
JADES researcher Jake Helton of Steward Observatory and the University of Arizona also identified that JADES-GS-z14-0 was detected at longer wavelengths with Webb’s Mid-Infrared Instrument (MIRI). And that’s a remarkable achievement considering its distance. The MIRI observation covers wavelengths of light emitted in the visible-light range, which are redshifted out of reach for Webb’s near-infrared instruments.
Jake’s analysis indicates the brightness of the source implied by the MIRI observation is above what would be extrapolated from the measurements by the other Webb instruments. And so it indicates the presence of strong ionized gas emission in the galaxy in the form of bright emission lines from hydrogen and oxygen. The presence of oxygen so early in the life of this galaxy is a surprise. It suggests multiple generations of very massive stars had already lived their lives before we observed the galaxy.
Distant, luminous galaxy will be one of many
Carniani and Hainline noted:
All these observations, together, tell us that JADES-GS-z14-0 is not like the types of galaxies that have been predicted by theoretical models and computer simulations to exist in the very early universe. Given the observed brightness of the source, we can forecast how it might grow over cosmic time. And so far we have not found any suitable analogs from the hundreds of other galaxies we’ve observed at high redshift in our survey.
Given the relatively small region of the sky that we searched to find JADES-GS-z14-0, its discovery has profound implications for the predicted number of bright galaxies we see in the early universe, as discussed in another concurrent JADES study (Robertson et al., recently accepted). It is likely that astronomers will find many such luminous galaxies, possibly at even earlier times, over the next decade with Webb. We’re thrilled to see the extraordinary diversity of galaxies that existed at Cosmic Dawn!
This post highlights data from Webb science in progress, which has not yet been through the peer-review process.
Bottom line: Astronomers using the Webb space telescope have discovered the most distant galaxy yet known. It existed 290 million years after the Big Bang.
Source: A shining cosmic dawn: spectroscopic confirmation of two luminous galaxies at z ~ 14
Via NASA