Home Blog Researchers have located oldest galaxy ever observed in Webb’s First Deep Field: Digital Photography Review

Researchers have located oldest galaxy ever observed in Webb’s First Deep Field: Digital Photography Review

by Amelia
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Image credit: Naidu et al, P. Oesch, T. Treu, GLASS-JWST, NASA/CSA/ESA/STScI

When NASA revealed the first image from the James Webb Space Telescope, it made a strong, immediate impact. The image, known as ‘Webb’s First Deep Field,’ contains thousands of galaxies and shows galaxy cluster SMACS 0723. The image is a composite that took about 12.5 hours to capture and includes detail captured across many different wavelengths. By now, we’ve all seen the image. However, there’s much more to the image than meets the eye.

New research reveals that one of the many galaxies in Webb’s First Deep Field is the oldest galaxy ever photographed by a telescope, breaking a record Hubble set in 2016. The previous record holder is the galaxy GN-z11, which you can see in the video below from March 2016.

The newly observed, more distant galaxy, GLASS-z13, is seen as it appeared about 300 to 400 million years after the big bang. That means the light from the distant galaxy is at least 13.5 billion years old.

GLASS-z13. The galaxy, located in Webb’s First Deep Field, is the oldest, most distant galaxy ever observed. Credit: Naidu et al, P. Oesch, T. Treu, GLASS-JWST, NASA/CSA/ESA/STScI

While Hubble’s ongoing work remains impressive and its now-broken record remains incredible, the space telescope is limited when viewing extremely deep galaxies ‘due to the limit of its wavelength coverage at 1.6 μm.’ In contrast, Webb delivers ‘an unprecedented view of the Universe at ∼ 2−5 μm thanks to the extremely sensitive NIRCam instrument.’

The researchers didn’t only find GLASS-z13, they also ‘We found two very compelling candidates for extremely distant galaxies,’ researcher Rohan Naidu told New Scientist. ‘If these galaxies are at the distance we think they are, the universe is only a few hundred million years old at that point.’ The researchers also outlined that the two galaxies, GLASS-z13 and GLASS-z11, are relatively small. The Milky Way galaxy is about 100,000 light-years in diameter, whereas GLASS-z13’s diameter is about 1,600 light-years, and the more distant GLASS-z11’s is about 2,300 light-years.

Figure 3. Absolute UV magnitude vs. Redshift for a representative sample of known galaxies in the first billion years of the Universe. Galaxies with photometric redshifts, sourced from Bouwens et al. (2022), are shown as points, and those with spectroscopic redshifts compiled from the literature as squares. The candidates presented in this work are depicted as purple stars, and populate a hitherto unoccupied region of parameter space. The brightness of these sources present a unique opportunity to efficiently extend the spectroscopic frontier to the first few hundred Myrs after the Big Bang.’

Credit: Naidu et al, P. Oesch, T. Treu, GLASS-JWST, NASA/CSA/ESA/STScI. Click here to read the full research paper, ‘Two Remarkably Luminous Galaxy Candidates at z ≈ 11 − 13 Revealed by JWST

One of Webb’s key mission objectives is to observe galaxies further back than Hubble, and the telescope has already eclipsed Hubble’s impressive record in its very early days. Don’t count Hubble out yet, though, as it is still performing critical research. Earlier this year, Hubble detected light from an individual star that existed within the first billion years following the big bang, making it the farthest individual star ever seen. The light from that star took 12.9 billion years to reach Hubble.

Figure 4. Results of the GALFIT morphology analysis for our two sources (GL-z11 top and GL-z13 bottom). The different columns from left to right correspond to the original data (in the F444W filter), the model, and the residual. The sizes and Sersic profiles of both sources are well constrained. GL-z11 shows some clear extension, consistent with a disk galaxy of 0.7 kpc at z ∼ 11. GL-z13 appears quite compact with an estimated size of 0.5 kpc.’

Credit: Naidu et al, P. Oesch, T. Treu, GLASS-JWST, NASA/CSA/ESA/STScI. Click here to read the full research paper, ‘Two Remarkably Luminous Galaxy Candidates at z ≈ 11 − 13 Revealed by JWST

The researchers from the Harvard and Smithsonian Center of Astrophysics in Massachusetts will continue to dig into the data that Webb has provided. The team expected JWST to see distant galaxies, but Naidu said, ‘we’re a little surprised how easy it is to detect them.’ Considering that Webb has only just started its scientific operations, it’s easy to imagine the space telescope helping researchers make even more incredible discoveries in the coming months and years. Who knows how long this new record will last?

The full draft of the new research paper is available here. The final section of the paper offers an optimistic look toward the future of JWST and astrophysics, ‘If these candidates are confirmed spectroscopically, and indeed two z ≈ 11 − 13 candidates lie awaiting discovery in every ∼50 arcmin2 extragalactic field, it is clear that JWST will prove highly successful in pushing the cosmic frontier all the way to the brink of the Big Bang.’


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