Scientists are pondering the nature of 300 mysterious objects that the James Webb Space Telescope has spotted in the depths of space. Most likely, these are incredibly bright young galaxies, but this assumption still needs to be verified.
Mysterious objects in James Webb’s images
Scientists from the University of Missouri are discussing whether the bright objects recorded in large numbers by the James Webb Space Telescope could be distant but bright galaxies, or something else.
In the first few years of operation, the new space observatory saw many more objects than any telescope. This led to a problem with sorting all the objects it discovered. Initially, 300 of them simply could not be classified.
“These mysterious objects are candidate galaxies in the early universe, meaning they could be very early galaxies,” said Haojing Yan, a professor of astronomy at the College of Arts and Sciences at Mizzou and co-author of the study. “If even a few of these objects turn out to be what we think they are, our discovery could challenge current ideas about how galaxies formed in the early universe—the period when the first stars and galaxies began to take shape.”
But identifying objects in space does not happen instantly. This requires a careful, step-by-step process to confirm their nature, combining advanced technology, detailed analysis, and several space detective investigations.
Step 1: Identifying the first clues
Mizzou’s researchers used two powerful infrared cameras on the JWST: the Near Infrared Camera and the Mid-Infrared Instrument. Both devices are specially designed to detect light from the most distant corners of space, which is key to studying the early Universe.
Why infrared? Because the farther away an object is, the longer its light travels to reach us. As light from these early galaxies travels through space, it stretches into longer wavelengths — shifting from visible light to infrared. This stretching is called redshift, and it helps us determine how far away these galaxies are. The higher the redshift, the farther the galaxy is from Earth, and the closer it is to the beginning of the Universe.
Step 2: “ The dropout”
To identify each of the 300 candidates for early galaxies, researchers at Mizzou used a well-known method called the “dropout” technique.
This method detects galaxies with high redshifts by examining objects that appear in redder wavelengths but disappear in bluer ones — a sign that their light has traveled vast distances and time. This phenomenon is an indicator of the “Lyman Break” — a spectral feature caused by the absorption of ultraviolet light by neutral hydrogen. As the redshift increases, this signal shifts toward redder wavelengths.
Step 3: Estimating the details
Once the “dropout” technique identifies each of the galaxy candidates, the next step is to check whether they could be at very high redshifts, Yan said.
“Ideally this would be done using spectroscopy, a technique that spreads light across different wavelengths to identify signatures that would allow an accurate redshift determination,” he said.
However, when complete spectroscopic data are not available, researchers can use a technique called spectral energy distribution fitting. This method provided Sun and Yan with a basis for evaluating the redshifts of their candidate galaxies, as well as other properties such as age and mass.
In the past, scientists commonly believed that these extremely bright objects were not early galaxies, but rather something that mimicked them. However, based on their achievements, Sun and Yan believe that these objects deserve closer attention and should not be dismissed so quickly.
Step 4: Final answer
The final test will use spectroscopy — the gold standard — to confirm the team’s findings.
Spectroscopy separates light into different wavelengths, just as a prism separates light into a rainbow of colors. Scientists use this technique to detect the unique fingerprint of a galaxy, which can tell them how old the galaxy is, its formation and composition.
“One of our objects is already confirmed by spectroscopy to be an early galaxy,” Sun said. “But this object alone is not enough. We will need to make additional confirmations to say for certain whether current theories are being challenged.”
According to phys.org
