A quiescent galaxy in a gas-rich cosmic web node at z∼3

Vol. 711
4. Extragalactic astronomy

A quiescent galaxy in a gas-rich cosmic web node at z∼3

A massive (Mstar ~ 10^11 solar masses) galaxy is discovered within a large-scale structure (MQN01) at z ≃3.25, containing one of the largest overdensities of galaxies and active galactic nuclei (AGNe). This galaxy has a very low star formation rate (4+6−2 M⊙/yr), placing it more than 1 dex below the star-forming main sequence, and it has no detectable molecular gas. The galaxy is located at the center of a large cool gas reservoir, as traced by bright Lyα and Hα emission, and in a gas reservoir that is kept cool and in a dynamically hot, turbulent state, by an external mechanism that reduces the ability of the gas to condense into a dynamically cold, efficiently star-forming disk. The suggested mechanism can be due to kinetic energy injected by an AGN jet in a nearby galaxy. Star formation rates of high-redshift galaxies could be substantially reduced and maintained at a low level even within gas-rich and overdense environments.