2025/10/13 by Bevacqua, Davide, Marchesini, Danilo, Saracco, Paolo +16 · 1 citation
#Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2510.11455
We report the spectroscopic detection of neutral gas inflow into a massive (M_* ≃ 4× 1010 M_\odot) quiescent galaxy observed at z_\rmspec = 2.6576 with JWST. From the redshifted absorption of the NaI doublet at λλ5890, 5896 Ang, we estimate an inflow velocity v=278+79-79 km s-1 and a column density log(NNaI/\rmcm2) = 13.02+0.03-0.03. We derive the inflowing mass of the gas Min = 1.6+0.1-0.1 × 108 M_\odot and rate Min = 19+6-7 M_\odot \rmyr-1. The presence of several surrounding galaxies suggests that the galaxy may be accreting gas from nearby companions. However, we cannot confirm it with current data and the intergalactic medium or cosmic filaments are also viable sources of the inflowing gas. Despite the ongoing inflow, the galaxy remains quiescent, with an upper limit to the star formation rate of 0.2 M_\odot \rmyr-1. Moreover, its star formation history suggests that the galaxy has remained quiescent during the past ∼1 Gyr, with half of its stars formed by redshift z50=11+18-3. We discuss that the inflow is not massive, dense, or long-lived enough to ignite significant star formation, or it is fueling low-level AGN activity instead. This is direct evidence that quiescent galaxies can accrete cold gas after their quenching while keeping their star formation subdued. Follow-up observations with JWST and ALMA will be needed to constraint the nature of the inflowing gas.