JWST’s 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
Astronomers report the most distant known galaxies, which have been discovered and confirmed by JWST.
An international team of astronomers has discovered the oldest and most distant galaxies confirmed to date using data from the James Webb Space Telescope (JWST). The telescope captured the light emitted by these galaxies more than 13.4 billion years ago, which means that the galaxies date back less than 400 million years after the Big Bang, when the universe was only 2% of its current age.
Initial observations from the JWST yielded several candidate galaxies at great distances, as did previous observations with the Hubble Space Telescope. Now, four of those targets have been confirmed by obtained long spectroscopic observations, which not only provide safe measurements of their distances, but also allow astronomers to characterize the physical properties of galaxies.
“We discovered galaxies at fantastically early times in the distant universe,” said Brant Robertson, professor of astronomy and astrophysics at the University of California, Santa Cruz. “With JWST, for the first time, we can now find such distant galaxies and then confirm with spectroscopy that they really are far away.”
Astronomers measure the distance to a galaxy by determining its redshift. Due to the expansion of the universe, distant objects appear to recede from us and their light is stretched to longer, redder wavelengths by the Doppler effect. Photometric techniques based on images captured through various filters can provide redshift estimates, but final measurements require spectroscopy, which separates light from an object into component wavelengths.
(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)
The new results focus on four galaxies with a redshift higher than 10. Two galaxies initially observed by Hubble confirmed redshifts of 10.38 and 11.58. The two most distant galaxies, both detected in the JWST images, have redshifts of 13.20 and 12.63, making them the most distant galaxies confirmed by spectroscopy to date. A redshift of 13.2 corresponds to about 13.5 billion years.
“These are much further afield than we ever imagined would have been discovered prior to JWST,” said Robertson. At redshift 13, the universe is only 325 million years old.
Robertson and Emma Curtis Lake of the University of Hertfordshire (UK) are the lead authors of two papers on findings that have not yet been through the peer-reviewed process (see links below).
The observations resulted from a collaboration of scientists who led the development of two of Webb’s onboard instruments, the Near Infrared Camera (NIRCam) and the Near Infrared Spectroradiometer (NIRSpec). The search for fainter, older galaxies was the main driver in the concepts for these instruments. In 2015, the instrument teams joined together to propose the JWST Advanced Deep Extragalactic Survey (JADES), an ambitious program that took just over one month of telescope time and is designed to provide a view of the early universe unprecedented in depth. and details. JADES is an international collaboration of more than eighty astronomers from ten countries.
“These results are the culmination of why the NIRCam team and NIRSpec have come together to implement this monitoring program,” said Marcia Rieke, principal investigator for NIRCam at the University of Arizona.
The JADES program began with NIRCam, using more than 10 days of mission time to observe a small patch of sky in and around the Hubble Ultra-Depth Field. Astronomers have been studying this region for more than 20 years using almost all large telescopes. The JADES team observed the field in nine different ranges of infrared wavelengths, capturing remarkable images that reveal nearly 100,000 distant galaxies, billions of light-years each.
The team then used the NIRSpec spectrometer for one observation period of three days to collect light from 250 faint galaxies. This yielded accurate redshift measurements and revealed the properties of the gas and stars in these galaxies.
“With these measurements, we can learn the intrinsic brightness of galaxies and find out how many stars they have,” said Robertson. “Now we can really begin to map out how galaxies come together over time.”
Co-author Sandro Tequila of the University of Cambridge in the UK added, “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. Plenty of questions about galaxies await the transformative opportunity.” Webb, and we’re thrilled to be able to play a part in revealing this story.”
According to Robertson, star formation in these early galaxies would have begun roughly 100 million years before the age in which they were observed, pushing the formation of the first stars to about 225 million years after.[{” attribute=””>Big Bang.
“We are seeing evidence of star formation about as early as we could expect based on our models of galaxy formation,” he said.
Other teams have identified candidate galaxies at even higher redshifts based on photometric analyses of JWST images, but these have yet to be confirmed by spectroscopy. JADES will continue in 2023 with a detailed study of another field, this one centered on the iconic Hubble Deep Field, and then a return to the Ultra Deep Field for another round of deep imaging and spectroscopy. Many more candidates in the field await spectroscopic investigation, with hundreds of hours of additional time already approved.
For more on this research, see NASA’s Webb Space Telescope Discovers Earliest Galaxies in the Universe.
References:
“Discovery and properties of the earliest galaxies with confirmed distances” by B. E. Robertson, S. Tacchella, B. D. Johnson, K. Hainline, L. Whitler, D. J. Eisenstein, R. Endsley, M. Rieke, D. P. Stark, S. Alberts, A. Dressler, E. Egami, R. Hausen, G. Rieke, I. Shivaei, C. C. Williams, C. N. A. Willmer, S. Arribas g, N. Bonaventura, A. Bunker, A. J. Cameron, S. Carniani, S. Charlot, J. Chevallard, M. Curti, E. Curtis-Lake, F. D’Eugenio, P. Jakobsen, T. J. Looser, N. Lützgendorf, R. Maiolino, M. V. Maseda, T. Rawle, H.-W. Rix, R. Smit, H. Übler, C. Willott, J. Witstok, S. Baum, R. Bhatawdekar, K. Boyett, Z. Chen, A. de Graaff, M. Florian, J. M. Helton, R. E. Hviding, Z. Ji, N. Kumari, J. Lyu, E. Nelson, L. Sandles, A. Saxena, K. A. Suess, F. Sun, M. Topping and I. E. B. Wallace, 17 November 2022, Astrophysics > Astrophysics of Galaxies.
arXiv:2212.04480
“Spectroscopic confirmation of four metal-poor galaxies at z=10.3-13.2” by Emma Curtis-Lake, Stefano Carniani, Alex Cameron, Stephane Charlot, Peter Jakobsen, Roberto Maiolino, Andrew Bunker, Joris Witstok, Renske Smit, Jacopo Chevallard, Chris Willott, Pierre Ferruit, Santiago Arribas, Nina Bonaventura, Mirko Curti, Francesco D’Eugenio, Marijn Franx, Giovanna Giardino, Tobias J. Looser, Nora Lützgendorf, Michael V. Maseda, Tim Rawle, Hans-Walter Rix, Bruno Rodriguez del Pino, Hannah Übler, Marco Sirianni, Alan Dressler, Eiichi Egami, Daniel J. Eisenstein, Ryan Endsley, Kevin Hainline, Ryan Hausen, Benjamin D. Johnson, Marcia Rieke, Brant Robertson, Irene Shivaei, Daniel P. Stark, Sandro Tacchella, Christina C. Williams, Christopher N. A. 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, Katherine A. Suess, Fengwu Sun, Michael W. Topping, Imaan E. B. Wallace and Lily Whitler, 8 December 2022, Astrophysics > Astrophysics of Galaxies.
arXiv:2212.04568
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