DeepDive: Neutral gas outflows in z~3.5 quiescent galaxies
PengPei Zhu (DTU Space/Cosmic Dawn Center)
Tuesday 16/12/2025 @ 14:30, Sala Antonio Sollima (IV piano Battiferro)
Neutral gas outflows play a key role in the baryon cycle of galaxies; their properties provide key insights into the transition from star formation to quiescence. We present the neutral gas outflow properties of 23 massive (M_star~10¹¹ M?) quiescent galaxies at redshift 2.8–4.6 from the DeepDive survey, a recent JWST/NIRSpec (R?1000) spectroscopy and NIRCam imaging program targeting massive quiescent systems at z > 3. Using the Na I doublet absorption lines, we detect excess absorption in 13/23 galaxies, with 11 showing blue-shifted features >200 km/s. We estimate mass outflow rates and identify the most extreme neutral-gas outflow rate (~10^2.7 M?/yr) yet reported beyond the local universe. For all 11 detections, the outflow rate can suppress ongoing SFR, though the gas likely fails to escape, implying fountain-like recycling. The z ~ 3 systems show distributions similar to those of their local counterparts in the SFR–velocity plane, but are offset by ~+350 km/s in the same age bin. All Na I-detected galaxies fall in the LINER region of the BPT diagram, suggesting possible AGN activity, though the role of these outflows in quenching star formation remains uncertain.