Webb observations challenge the cosmic dust formation hypothesis

British scientists have observed through the Webb Space Telescope that there is carbon dust in galaxies less than 1 billion years old. These elements are heavier than hydrogen and helium and are thought to be features only found in older galaxies over 13 billion years old, such as the Milky Way. This latest discovery could challenge existing hypotheses about the formation of cosmic dust. The study was recently published in Nature.

Interstellar dust is produced in dying stars and is therefore considered a marker of galaxy evolution. It is thought that heavier elements such as carbon were scarce in quantities in the early universe. Conversely, older galaxies such as the Milky Way are thought to have carbon dust grains – such as aromatic hydrocarbons – due to observed “humps” in the absorption of light at specific ultraviolet frequencies.

Joris Witstok of the University of Cambridge and colleagues used Webb to observe a hump-like absorption of ultraviolet light from much younger galaxies, including a galaxy that existed only about 1 billion years after the Big Bang, suggesting that there is carbonaceous dust in the galaxy. These findings challenge existing assumptions about dust formation, which suggest that heavier elements do not form as quickly.

The researchers believe that the relatively short time for carbon particles to form in this early galaxy means that there is a rapid production process, such as from the rapidly forming star Wolf-Rayet star, or from supernova ejecta.

“This work made a significant contribution to empirical data on dust and chemical evolution in the early universe, effectively reducing the time distance between the reported observations and the beginning of the universe in half, approaching the limit at which galaxy formation is thought to occur.” These data should help shape the theory of galaxy evolution. An international reviewer said. (Source: China Science News, Jinnan)

Cosmic picture taken by Webb. Image courtesy of NASA

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