SciTechDaily.com
American astronomers from University of Missouri with the help of the James Webb Space Telescope (JWST), found about 300 candidates for the role of of early galaxies.
In a recent study based on observations of distant regions of the Universe, a group of astronomers from The University of Missouri has made unexpected discovery. They analyzed the infrared images taken by JWST and found 300 objects, whose brightness was higher than expected.
“These mysterious objects are potential galaxies in the early Universe, which means they could be very early galaxies. If at least a few of these objects turn out to be what, we think they are, our discovery could challenge current ideas about the formation of galaxies in the early Universe — the period when the first stars and galaxies began to form”, — emphasizes the study’s co-author, is a professor of astronomy at the Mizzou College of Arts and Sciences, Haojing Yan.
Identification of space objects — a lengthy process that requires a thorough analysis using sophisticated technology and modeling. Researchers from the College Mizzou College of Arts and Sciences began their research, using JWST’s near-infrared camera and mid-infrared instrument. These instruments allow us to capture light coming from the farthest reaches of the Universe.
“As the light from these early galaxies travels through space, it is stretched into longer wavelengths, moving from visible light to infrared. This stretch is called the redshift, and it helps us determine how far away these galaxies are. The larger the redshift, the further away the galaxy is from us and the closer it is to the beginning of the Universe”, — Haojing Yan explains.
To identify each of the 300 potential early galaxies, the researchers used the method of exclusion. As the lead author of the study notes Banzheng “Tom” Sun, JWST detects galaxies with a large redshift and tracks objects that appear in redder wavelengths but disappear in blue wavelengths — a sign that the light from these objects traveled a long distance over a long period of time.
“This indicates a “Lyman breakthrough” — a spectral feature, caused by the absorption of ultraviolet light by neutral hydrogen. As the redshift increases, this signature shifts toward redder wavelengths”, — adds Banzhen Sun.
As emphasized by Haojing Yan, while the exclusion method allows us to identify each of the candidate galaxies, the next step is to check whether they may be at “very” large redshifts. The researcher suggests, that ideally, this would be done using spectroscopy — a method that distributes light over different wavelengths to detect features that will allow for accurate redshift detection.
However, if full spectroscopic data are not available, astronomers can use the so-called “method of fitting the spectral distribution of energy”. This method provided the researchers with the basic basis for estimating the redshift of their galaxy candidates, as well as other characteristics such as age and mass.
For a long time, scientists have been inclined to believe, that these extremely bright objects are not early galaxies, but instead something else, that mimics the light from such galaxies. However, the new study suggests that these objects deserve a more thorough study.
In the last test, — gold standard spectroscopy will be used to confirm the group’s findings. Spectroscopy decomposes light into wavelengths of different lengths, much like a prism splits light into a rainbow of colors. Scientists use this method to reveal a galaxy’s unique fingerprint, which can tell them its age, how it formed, and what it is made of.
The results of the study were published in the journal Astrophysical Journal
Source: SciTechDaily
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