2023/08/28 by M. Stiavelli, Stiavelli, Massimo, Takahiro Morishita +14 · 1 citation
Physics and Astronomy · #Astronomy and Astrophysical Research #Galaxies: Formation, Evolution, Phenomena #Gamma-ray bursts and supernovae
paper · pdf · doi:10.48550/arxiv.2308.14696
We analyze new JWST NIRCam and NIRSpec data on the redshift 9.11 galaxy MACS1149-JD1. Our NIRCam imaging data reveal that JD1 comprises three spatially distinct components. Our spectroscopic data indicate that JD1 appears dust-free but is already enriched, 12 + log \rm (O/H) = 7.90+0.04-0.05. We also find that the Carbon and Neon abundances in JD1 are below the solar abundance ratio. Particularly the Carbon under-abundance is suggestive of recent star formation where Type~II supernovae have already enriched the ISM in Oxygen but intermediate mass stars have not yet enriched the ISM in Carbon. A recent burst of star formation is also revealed by the star formation history derived from NIRCam photometry. Our data do not reveal the presence of a significant amount of old populations, resulting in a factor of ∼7× smaller stellar mass than previous estimates. Thus, our data support the view that JD1 is a young galaxy.