RAS: Astronomers Confirm Age of Most Distant Galaxy

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RAS: Astronomers Confirm Age of Most Distant Galaxy

Post by bystander » Fri Jan 27, 2023 4:14 pm

Astronomers Confirm Age of Most Distant Galaxy
Royal Astronomical Society | 2023 Jan 24
Image of galaxy GHZ2/GLASS-z12 with the 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 due to the expansion of the Universe since the line was emitted.
Image 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 distant galaxy. The team used the ALMA radio telescope array to detect a radio signal that has been travelling for approximately 97% of the age of the Universe. This discovery confirms the existence of galaxies in the very early Universe found by the James Webb Space Telescope. ...

The galaxy, named GHZ2/GLASS-z12, was initially identified in the JWST GLASS survey, a survey that observes the distant Universe and behind massive clusters of galaxies. These observations consist of several images using different broad-band colour filters, similar to the separate RGB colours in a camera. For distant galaxies, the light takes such a long time to reach us that the expansion of the Universe has shifted the colour of this light towards the red end of the visible light spectrum in the so-called redshift. The red colour of GHZ2/GLASS-z12 consequently helped researchers identify it as one of the most convincing candidates for a distant galaxy they observed.

So many bright distant galaxies were identified in the first few weeks of JWST observations that it challenged our basic understanding of the formation of the earliest galaxies. However, these red colours are only indicative of a distant galaxy, and could instead be a very dust-rich galaxy masquerading as a more distant object. Only direct observations of spectral lines – lines present in a galaxy’s light spectrum used to identify the elements present – can robustly confirm the true distances of these galaxies.

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

Deep ALMA Redshift Search of a z ~ 12 GLASS-JWST Galaxy Candidate ~ Tom J. L. C. Bakx et al
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