Spiral galaxies are among the most beautiful objects in the cosmos. Among these, spiral galaxies in the far reaches of the universe hold important clues to their genesis and development. However, because these galaxies are too far away to investigate in detail, we only have a limited comprehension of them. The limited spatial resolution and/or sensitivity of these galaxies prevented us from studying their precise shapes and properties, according to junior researcher Yoshinobu Fudamoto from Waseda University in Japan, who has been studying the evolution of galaxies. “These galaxies were already detected among the previous observations using NASA’s Hubble Space Telescope and Spitzer Space Telescope,” he says.
The James Webb Space Telescope (JWST), operated by NASA, has advanced the situation. JWST has successfully captured infrared photos of a population of red spiral galaxies in the galaxy cluster SMACS J0723.3-7327 at an unprecedented resolution, revealing their morphology in detail!
In light of this, a group of researchers led by Waseda University and Japan’s Prof. Akio K. Inoue and Dr. Yuma Sugahara presented unexpected insights on these red spiral galaxies in a recent study that was published in The Astrophysical Journal Letters on October 21, 2022. The researchers concentrated on the two reddest galaxies, RS13 and RS14, out of the several red spiral galaxies they found. The researchers determined the distribution of energy over a broad wavelength range for these galaxies using spectral energy distribution (SED) analysis. According to the SED analysis, these red spiral galaxies originated in the early cosmos at “cosmic noon” (8–10 billion years ago), a time that came after the Big Bang and the “cosmic dawn.” Surprisingly, these spiral galaxies are among the farthest yet identified.
Only 2% of the galaxies in the nearby cosmos are rare, red spiral galaxies. The fact that red spiral galaxies were discovered in the early cosmos from a JWST scan that only covered a small portion of space shows that there were many of these galaxies around at that time.
Contrary to the intuitive expectation that galaxies in the early universe would be actively producing stars, the researchers also found that one of the red spiral galaxies, RS14, is a “passive” (not forming stars) spiral galaxy. This discovery of a passive spiral galaxy inside the JWST’s narrow field of view is especially unexpected since it raises the possibility that there were numerous passive spiral galaxies in the early universe.
Overall, this study’s findings greatly expand our understanding of both the universe and red spiral galaxies. “For the first time, our research demonstrated that passive spiral galaxies might have been prevalent in the early cosmos.” Although this paper is only a pilot investigation into spiral galaxies in the early universe, its confirmation and development would have a significant impact on our comprehension of the origin and development of galaxy morphologies. “Fudamoto comes to an end.
