NASA’s Webb Space Telescope discovers the oldest galaxies in the universe

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Artist’s conception of the Webb Telescope in space. Credit: NASA

Astronomers report on the most distant galaxies known – discovered and confirmed by the James Webb Space Telescope.

As the most powerful space telescope ever built, NASA’s James Webb has unparalleled capabilities to observe the most distant galaxies in the universe, much like a cosmic time machine. In fact, it is said to be 5-10 times better than any other telescope at measuring distant galaxies. Now, less than a year after launch and only 5 months after he was fully ready for science, Webb has been used to discover the oldest galaxies confirmed to date.

An international team of astronomers has used data from NASA’s James Webb Space Telescope (JWST) to report the discovery of the oldest galaxies confirmed to date. The light from these galaxies took more than 13.4 billion years to reach us, as these galaxies date back less than 400 million years after the Big Bang, when the universe was only 2% of its current age.

Previous data from Webb have provided candidates for such nascent galaxies. Now, those targets have been confirmed by acquisition of spectroscopic observations, revealing distinct, distinct patterns in the light signatures coming from these incredibly faint galaxies.

“It was necessary to prove that these galaxies did indeed inhabit the early universe. It is very possible that even closer galaxies disguised themselves as very distant galaxies,” said astronomer and co-author Emma Curtis-Lake of the University of Hertfordshire in the UK. “Seeing the spectrum unfolded as we had hoped , confirming that these galaxies are at the true edge of our view, and some of them are farther away than Hubble can see! It’s a very exciting accomplishment of the mission.”

The JWST Advanced Deep Extragalactic Survey (JADES) focused on the region in and around the Hubble Space Telescope’s ultra-deep field. Using Webb’s NIRCam instrument, the scientists observed the field in nine different infrared wavelength ranges. From these images (displayed left), the team searched for faint galaxies that are visible in the infrared but whose spectra abruptly break off at a critical wavelength known as the Lyman fracture. The Webb NIRSpec instrument then provided an accurate measure of the redshift for each galaxy (shown at right). Four of the galaxies studied are particularly special, as they were revealed to be in an unprecedentedly early era. These galaxies date back less than 400 million years after the Big Bang, when the universe was only 2% of its current age. In the background image, blue represents light at 1.15 microns (115 W), green is 2.0 microns (200 W), and red is 4.44 microns (444 W). In the cutout images, blue is a mixture of 0.9 and 1.15 microns (090W + 115W), green is 1.5 microns (150W + 200W), and red is 2.0, 2.77, and 4.44 microns (200W + 277W + 444W) . Credit: NASA, ESA, CSA, STScI, M. Zamani (ESA/Webb), and L. Hustak (STScI). Sciences: B. Robertson (UCSC), S. Tacchella (Cambridge), E. Curtis-Lake (Hertfordshire), S. Carniani (Scuola Normale Superiore), and JADES Collaboration

The observations resulted from a collaboration of scientists who led the development of two of the instruments aboard Webb, the Near Infrared Camera (NIRCam) and the Near Infrared Spectroradiometer (NIRSpec). The search for fainter, older galaxies was the main driving force behind these instrument concepts. In 2015, the instrument teams joined together to propose the JWST Advanced Deep Extragalactic Survey (JADES), an ambitious program devoted to just over one month of telescope time over two years and designed to provide a view of the early universe unprecedented in depth and detail. JADES is an international collaboration of more than eighty astronomers from ten countries. “These findings are the culmination of why the NIRCam and NIRSpec teams joined together to implement this monitoring program,” said co-author Marcia Rickam, NIRCam principal investigator, of the University of Arizona in Tucson.

The first round of JADES observations focused on the region in and around the Hubble Space Telescope’s Ultra Deep Field (see image below). For more than 20 years, this small patch of sky has been the target of nearly all large telescopes, building an exceptionally sensitive data set spanning the entire electromagnetic spectrum. Webb now adds its unique width, providing the softest and sharpest images ever obtained.

This view of nearly 10,000 galaxies is called the Hubble Ultra Deep Field. The snapshot includes galaxies of various ages, sizes, shapes, and colors. The smallest and reddest galaxies may be among the most distant galaxies known, having existed when the universe was only about 800 million years old. The earliest galaxies — the larger, brighter, well-defined spirals and ellipticals — flourished about a billion years ago, when the universe was 13 billion years old. The image required 800 exposures taken over 400 Hubble orbits around Earth. The total exposure time was 11.3 days, taken between Sept. 24, 2003, and Jan. 16, 2004. Credit: NASA, ESA, S. Beckwith (STScI), and the HUDF team

The JADES program began with NIRCam, using more than 10 days of mission time to monitor the field in nine different colors of infrared, producing gorgeous images of the sky. The region is 15 times larger than the deepest infrared images produced by the Hubble Space Telescope, yet it is deeper and sharper at these wavelengths. The image is only the size a human would appear when viewed from a mile away. However, it is teeming with nearly 100,000 galaxies, each discovered at some point in its history, billions of years in the past.

“For the first time, we detected galaxies only 350 million years after the Big Bang, and we can be absolutely confident of their remarkable distances,” said co-author Brant Robertson of the University of California Santa Cruz, a member of the NIRCam science team. “Finding these early galaxies in such stunningly beautiful images is a special experience.”

This image from the James Webb Space Telescope highlights an area studied by the JWST Advanced Deep Extragalactic Survey (JADES). This region lies in and around the ultra-deep field of the Hubble Space Telescope. The scientists used Webb’s NIRCam instrument to observe the field in nine different infrared wavelength ranges. From these images, the team searched for faint galaxies that could be seen in the infrared but whose spectra abruptly cut off at a critical wavelength. They made additional observations (not shown here) using Webb’s NIRSpec instrument to measure the redshift of each galaxy and reveal the properties of the gas and stars in these galaxies. In this image, blue represents light at 1.15 microns (115 W), green is 2.0 microns (200 W), and red is 4.44 microns (444 W). Credit: NASA, ESA, CSA, and M. Zamani (ESA/Webb). Science: B. Robertson (UCSC), S. Tacchella (Cambridge), E. Curtis-Lake (Hertfordshire), S. Carniani (Scuola Normale Superiore), and JADES Collaboration.

From these images, galaxies in the early universe can be distinguished by the telltale aspect of their multi-wavelength colors. Light stretches in wavelength as the universe expands, and the light from these smaller galaxies expands by a factor of up to 14. Astronomers look for faint galaxies that can be seen in the infrared but whose light is suddenly cut off at a critical wavelength. The location of the cutoff within each galaxy’s spectrum is shifted by the expansion of the universe. The JADES team scanned Webb’s photos for these special candidates.

They then used the NIRSpec instrument, for one observation period spanning three days totaling 28 hours of data collection. The team collected the light from 250 fainter galaxies, allowing the astronomers to study the patterns imprinted on the spectrum by the atoms in each galaxy. This resulted in an accurate measurement of the redshift of each galaxy and revealed the properties of the gas and stars in these galaxies.

(Click on the image to see the full graph.) The universe is expanding, and that expansion is expanding light that travels through space in a phenomenon known as the cosmic redshift. The greater the redshift, the greater the distance the light has traveled. As a result, telescopes with infrared detectors are necessary to see the light from the first and most distant galaxies. Credit: NASA, ESA, and L. Hustak (STSci)

“These are by far the weakest infrared spectra ever captured,” said astronomer and co-author Stefano Cargnani of Scuola Normale Superiore in Italy. “It reveals what we hoped to see: an accurate measurement of the wavelength of light due to intergalactic hydrogen scattering.”

Four of the galaxies studied are particularly special, as they were revealed to be in an unprecedentedly early era. The results provided spectroscopic confirmation that these four galaxies lie at redshifts above 10, including two at redshift 13. This corresponds to a time when the universe was about 330 million years old, setting new frontiers in the search for distant galaxies. These galaxies are very faint due to their great distance from us. Astronomers can now explore their properties, thanks to Webb’s remarkable sensitivity.

Hubble Deep Field image. Released January 15, 1996. Credit: R. Williams (STScI), Hubble Deep Field Team, NASA

Astronomer and co-author Sandro Tequila of the University of Cambridge in the UK explained, “It is difficult to understand galaxies without understanding the initial periods of their evolution. As with humans, much of what happens later depends on the influence of these early generations of stars. Lots of questions about galaxies await.” A transformative opportunity for Webb, and we are thrilled to be able to play a part in uncovering this story.”

JADES will continue in 2023 with a detailed study of another field, this one centered on the iconic Hubble Deep Field (see image above), and then return to the Ultra Deep Field for another round of deep imaging and spectral analysis. Many candidates in this field await spectral investigation, with hundreds of hours of additional time already approved.

Note: This post highlights data from Webb’s Science in Progress, which has not yet been through the peer-review process.

References:

“Discovery and Characteristics of the Oldest Galaxies with Confirmed Distances” by P. Robertson, S. Tequila, BD Johnson, K. Heinlein, L. Whitler, D.J. Eisenstein, R. . Dressler, E. Igami, R. Hausen, J. Rick, I. Shifay, C. C. Williams, CNA Wilmer, S. Arribas, N. Bonaventura, A. Banker, AJ Cameron, S. Cargnani, S. Charlotte, J. Chevallard, M. Curti, E. Curtis-Lake, F. D’Eugenio, P. Jakobsen, TJ Looser, N. Lützgendorf, R. Maiolino, MV Maseda, T. Rawle, H. -W. Rex, R. Smit, H. Obler, C. Willott, J. Wittstock, S. Baum, R, Pataudekar, K. Boyett, Z. Chen, Graf AD, M. Florian JM Hilton, R Heviding Z. Ji, N. Kumari, J. Lyu, E. Nelson, L. Sandles, A. Saxena, KA Suess, F. Sun, M. Topping and IEB Wallace, 8 December 2022, Astrophysics > Astrophysics of Galaxies.arXiv:2212.04480

“Spectral analysis of four metal-poor galaxies beyond tenth redshift” By Emma Curtis Lake, Stefano Cargnani, Alex Cameron, Stefan Charlot, Peter Jacobsen, Roberto Maiolino, Andrew Banker, Joris Wittstock, Rynsky-Smit, Jacobo Chevallard, Chris Willot, Pierre Veruet, Santiago Arribas, Nina Bonaventura, Mirko Corti, Francesco Diogenio, Marine Francs, Giovanna Giardino, Tobias J. Loeser, Nora Lutzgendorf, Michael V. Maceda, Tim Rawley, Hans Walter Rex, Bruno Rodriguez Del Pino, Hana Obler, Marco Siriani, Alan Dressler, Icchi Egami, Daniel J. Eisenstein, Ryan Endsley, Kevin Heinlein, Ryan Hausen, Benjamin D. Johnson, Marcia Rickey, Brant Robertson, Erin Shivay, Daniel B. Stark, Sandro Tequila, Christina C. Williams, Christopher NA Willmer, Rachana Bhatawdekar, Rebecca Bowler, Kristan Boyett, Zuyi Chen, Anna de Graaff, Jakob M. Helton, Raphael E. Hviding, Gareth C. Jones, Nimisha Kumari, Jianwei Lyu, Erica Nelson, Michele Perna, Lester Sandles, Aayush Saxena, Kathryn A. Suess, Fengo Sun, Michael W. Topping, and Faith E.B. Wallace and Lily Whitler. PDF

The James Webb Space Telescope is the world’s premier space science observatory. Webb will solve mysteries in our solar system, look beyond to distant worlds around other stars, and probe mysterious structures and the origins of the universe and our place in it. Webb is an international program led by NASA with its partners ESA (European Space Agency) and CSA (Canadian Space Agency).

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