A brilliant missing phantom that was detected by terrestrial observatories and disappeared in images of the Hubble Space Telescope has reappeared as a dubious galaxy in an image of the James Webb. Astronomers from the COSMOS-Web collaboration have identified the AzTECC71 object as a star-forming dust galaxy. Or, in other words, a galaxy that is busy forming many new stars but that is wrapped in a veil of dust that is difficult to see through it, a thousand thousand years after the Big Bang.
Once upon a time it was thought that these galaxies were extremely rare in the early universe, but this discovery, like most of a series of additional candidates in the first half of the COSMOS-Web data that has not yet been described in the literature scientifically, I suggest that they could be three to 10 times more common than expected.
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How big is the galaxy detected by James Webb?
“This thing is a real monster,” said Jed McKinney, postdoctoral investigator of the University of Texas in Austin. “Although it seems like a small thing, in reality it is forming hundreds of new stars every year. And the fact that even so much extreme is barely visible in the most sensitive images of our new telescope is very exciting for me.
Potentially it tells us that there is a population of galaxies that have been hiding from us.” If this conclusion is confirmed, it would suggest that the primitive universe was much more dusty than what was previously thought. The team published its findings in The Astrophysical Journal .
The COSMOS-Web project, the largest initial investigation initiative of the JWST (James Webb Spacial Telescope), co-directed by Caitlin Casey, an associate professor at UT Austin, has the objective of mapping up to 1 million galaxies from a part of the sky within the span of three full moons. The objective in part is to study the most ancient structures of the universe. The team of more than 50 investigators received 250 hours of observation in the first year of the JWST and received a first batch of data in December 2022, and will receive more until the end of 2024.
Why was it so difficult to capture this galaxy for James Webb?
A dust-oriented galaxy formed by stars is difficult to view with optical light because much of the light from its stars is absorbed by a veil of dust and may be reemitted at longer (or larger) wave lengths. Before the JWST, astronomers often referred to it as “Hubble’s dark galaxies,” referring to the space telescope that was previously the most sensitive.
“Now, the only way we can see galaxies in the present universe is from an optical perspective with the Hubble,” said McKinney. “This means that our understanding of the history of the evolution of galaxies is broken because we are only seeing less dark and less dusty galaxies.”
This galaxy, AzTECC71, was first detected as an indistinct lack of dust emission from a camera of the James Clerk Maxwell Telescope in Hawaii that occurs at wave lengths between the infrared light and the microwave. Furthermore, the COSMOS-Web team detected the object in data collected by another team using the ALMA telescope in Chile, which has a higher spatial resolution and can be seen in infrared light. This allows you to delimit the location of the source. When they observed the JWST data in infrared light at a wave length of 4.44 microns, they encountered a faint galaxy exactly in that same location. At shorter light wave lengths, less than 2.7 microns, it was invisible.
Now, the team is working to discover more of these JWST débile galaxies. “With JWST, we can first study the optical and infrared properties of this population of hidden and very dark galaxies through the dust,” says McKinney, “because it is so sensitive that we can not only look at the furthest edges of the universe, but you can also get through the greater amount of dust particles”. The team estimates that the galaxy is being viewed with a red color of approximately 6, which translates into 900 million years after the Big Bang.
With information from Europa Press