Astronomers confirm the age of most distant galaxies using oxygen

Image of galaxy GHZ2/GLASS-z12 with associated ALMA spectrum. ALMA’s deep spectroscopic observations revealed a spectral emission line associated with ionized oxygen near the galaxy, which has been shifted in its observed frequency by the expansion of the universe since the line’s emission. Credit: NASA/ESA/CSA/T. Treu, UCLA/NAOJ/T. Bakx, Nagoya U

A new study led by a joint team at Nagoya University and the National Astronomical Observatory of Japan has measured the cosmic age of a very, very distant galaxy. The team used the ALMA Radio Telescope Array to detect a radio signal that has been traveling for about 97% of the age of the universe. This discovery confirms the existence of galaxies in the very early universe discovered by the James Webb Space Telescope. Research published in Monthly Notices of the Royal Astronomical Society.

The galaxy, named GHZ2/GLASS-z12, was initially identified in the JWST GLASS Survey, a survey observing the distant universe and behind massive clusters of galaxies. These notes are composed of several images using different wide-band color filters, similar to discrete RGB colors in a camera. For distant galaxies, the light takes so long to reach us that the expansion of the universe has shifted the color of that light toward the red end of the visible light spectrum in what’s called a redshift. Thus, the red color of GHZ2/GLASS-z12 helped researchers identify it as one of the most convincing candidates for a distant galaxy they have observed.

Many bright, distant galaxies identified in the first few weeks of JWST observations have challenged our basic understanding of the formation of the first galaxies. However, these red colors are only indicative of a distant galaxy, and could instead be a dust-rich galaxy masquerading as a more distant object. Only direct observations of spectral lines — the lines in a galaxy’s light spectrum used to identify the elements present — can firmly confirm the true distances of these galaxies.

Immediately after the discovery of these early candidate galaxies, two early-career researchers at Nagoya University and the Japan National Astronomical Observatory used 40 radio telescopes from the ALMA array in Chile to search for a spectral line to confirm the true ages of the galaxies.

ALMA referred GHZ2/GLASS-z12 to search for an emission line associated with oxygen at the expected frequency suggested by the JWST observations. Oxygen is a typically abundant element in distant galaxies due to its relatively short formation period, so the team chose to search for the oxygen emission line to increase the chances of detection.

Astronomers confirm the age of most distant galaxies using oxygen

The ALMA radio telescope array has accurately indicated the exact cosmic age of a distant galaxy determined by JWST, GHZ2/GLASS-z12, 367 million years after the Big Bang. ALMA’s deep spectroscopic observations revealed a spectral emission line associated with ionized oxygen near the galaxy, which has been shifted in its observed frequency due to the expansion of the universe since the line’s emission. This observation confirms that JWST is able to search for distances to record distances, and heralds a leap in our ability to understand the composition of the oldest galaxies in the universe. Credit: NASA/ESA/CSA/T. Treu, UCLA/NAOJ/T. Bakx, Nagoya U.

By combining the signal from both of its 12-meter telescopes, ALMA was able to detect the emission line close to the location of the galaxy. The observed redshift of the line indicates that we see the galaxy as it was only 367 million years after the Big Bang.

“The first images from the James Webb Space Telescope revealed so many early galaxies, that we felt we had to test its results with the best observatory on Earth,” said lead author Tom Bakx of Nagoya University. “It was a very exciting time to be an observational astronomer, and we could track the status of the observations that will test the JWST results in real time.”

“We were initially concerned about the slight discrepancy in position between the detected oxygen emission line and the galaxy that Webb saw,” notes author Tom Bax, “but we did detailed tests on the observations to confirm that this is a really strong finding, and it is very difficult to explain this by any other explanation.” “.

Adds co-author Jorge Zavala of the National Astronomical Observatory of Japan, “The bright line emission indicates that this galaxy has rapidly enriched its gaseous reservoirs with elements heavier than hydrogen and helium. This gives us some clues about the formation and evolution of the first generation of stars and their age. The separation may indicate The small amount we see among the oxygen gas and star emissions also indicates that these early galaxies experienced violent explosions that blew gas away from the galactic center into the perigalactic region and even beyond – on the other side.”

“These deep ALMA observations provide strong evidence for the existence of galaxies within the first hundreds of millions of years after the Big Bang, and confirm the surprising results from Webb’s observations. JWST’s work is just beginning, but we are already adjusting models of how galaxies formed in the early universe to match these observations. The combined power of Webb and the ALMA radio telescope array gives us the confidence to push our cosmic horizons closer to the dawn of the universe.”

more information:
Tom JLC Bakx et al., An ALMA redshift deep search for a candidate galaxy az∼12 GLASS-JWST, Monthly Notices of the Royal Astronomical Society (2022). DOI: 10.1093/mnras/stac3723

Provided by the Royal Astronomical Society

the quote: Astronomers Confirm Age of Most Distant Galaxies Using Oxygen (2023, January 25) Retrieved January 25, 2023 from https://phys.org/news/2023-01-astronomers-age-distant-galaxy-oxygen.html

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