Dense galaxies are carving out a bubble in the early universe

Researchers using JWST data have discovered an overdensity of galaxies in the early universe, which may be carving out a bubble of ionized hydrogen. The overdensity is located in the GOODS-S field and is about four times denser than the average galaxy distribution. The overdensity contains 18 galaxies in a comoving group, with a star formation rate that is nearly 50% of the total in the field. This finding suggests that the galaxies are interacting and may be responsible for the early stages of cosmic reionization. The researchers found Lyman-alpha transmissions, which are indicative of ionized hydrogen, and observed spatial variation in the Lyman-alpha radiation, consistent with the formation of an ionized bubble. The detection of this spatial variation could mark the earliest ionized bubble produced by a galaxy overdensity. The study is titled "JADES: A Prominent Galaxy Overdensity Candidate within the First 500 Myr," and the lead author is Zihao Wu from the Center for Astrophysics, Harvard & Smithsonian. The findings suggest that these galaxy overdensities could be responsible for initiating reionization, as they are interacting more than field galaxies but not experiencing rapid star formation. The detection of Lyman-alpha radiation provides evidence that the radiation is visible as it reaches the boundary of a reionized bubble. The researchers plan to observe the overdensity again with JWST and ALMA to map its three-dimensional structure and test its role in cosmic reionization.

AI-generated summary of the original article — see the source for the full story.