A team of astronomers has discovered a new massive and quiescent galaxy at a high redshift of 4.53. The galaxy, which has been designated COSMOS-1047519, was detected using the Keck/MOSFIRE spectrograph.
COSMOS-1047519 has a mass of about 60 billion solar masses and a star-formation rate (SFR) at a level of only 10 solar masses per year. The galaxy's stellar age is estimated to be 180 million years.
The astronomers believe that COSMOS-1047519 is likely a galaxy in the process of being quenched. The star formation history of the galaxy inferred from the SED fitting suggests that it experienced a starburst at a redshift of 5.0, followed by rapid quenching with a timescale of about 100 million years.
The discovery of COSMOS-1047519 is significant because it is one of the youngest quiescent galaxies at a redshift higher than 3.0. The findings also provide insights into the physical processes that are responsible for the suppression of star formation in massive galaxies.
The authors of the paper propose that gas depletion due to the starburst and/or AGN feedback triggered by galaxy-galaxy interactions or mergers may be responsible for quenching in COSMOS-1047519.
The discovery of COSMOS-1047519 is a reminder that the universe is a dynamic place, and that galaxies are constantly evolving. The findings of this study will help astronomers to better understand the processes that shape the evolution of galaxies over time.
Quote from the lead author:
"The discovery of COSMOS-1047519 is an exciting finding," said Takumi Kakimoto, the lead author of the paper. "This galaxy provides us with a unique opportunity to study the processes that are responsible for the quenching of star formation in massive galaxies at high redshifts."
Journal Information: Takumi Kakimoto et al, A massive quiescent galaxy in a group environment at z=4.53, arXiv (2023). DOI: 10.48550/arxiv.2308.15011