One of the design goals of the James Webb Space Telescope was to provide the ability to image at wavelengths that would reveal the first stars and galaxies in the universe. Now, a few weeks after revealing her first photos, we get a strong indication that she’s a hit. In some data released to the public by NASA, researchers have discovered up to five galaxies from the distant universe, which are already in existence only a few hundred million years after the Big Bang. If confirmed as far away as it appears, one of them would be the most distant galaxy observed so far.
For many of its observatories, NASA allows astronomers to submit observational proposals and allows these users exclusive access to the resulting data for a period afterward. But for its latest tools, NASA has a set of goals where the data will be announced instantly, for anyone to analyze as they please. Some of these include websites similar to One of the first pictures has been releasedwhere a large group of galaxies in the foreground act as a lens to magnify distant objects.
(You can look at the details One of the data sets used for this analysiscalled GLASS, which used the Abell 2744 cluster to magnify distant objects, which were magnified by a telescope.)
The images in this data set were long exposures made on different parts of the infrared spectrum. The entire range of wavelengths covered by the NIRCam instrument was divided into seven segments, and each segment was imaged for anywhere from 1.5 to 6.6 hours. A large international team of researchers used these pieces to perform an analysis that would help them identify distant galaxies by looking for things that were present in some parts of the spectrum but are missing from others.
The research was based on the understanding that most of the universe was filled with hydrogen atoms for hundreds of millions of years after the formation of the cosmic microwave background. These will absorb any light at or above a wavelength that is sufficient to ionize hydrogen, making the universe opaque for these wavelengths. At the time, this cut was somewhere at the ultraviolet end of the spectrum. But in the intervening period, the expansion of the universe has shifted this cut to the infrared part of the spectrum – one of the main reasons Webb’s design is to be sensitive to these wavelengths.
So the team looked for objects that were present in the images of the lower-energy segments of the infrared spectrum imaged by Webb but absent from the high-energy segments. The exact point at which it disappeared indicates how far the redshift is relative to that galaxy, and thus how far away the galaxy is. (You can expect future research to include a similar approach.)
This method produced five different things of interest, and the draft manuscript focuses on two of the most distant of these: GLASS-z13 and GLASS-z11. The first is beyond the farthest confirmed distance of anything observed in the Hubble Deep Field. If confirmed, this would make it the farthest object we know of, and thus the closest in time to the Big Bang.
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