Star Formation and Quenching of Central Galaxies from Stacked HI Measurements

Abstract

We quantitatively investigate the dependence of central galaxy Hi mass (M HI ) on the stellar mass (M * ), halo mass (M h ), star formation rate (SFR), and central stellar surface density within 1 kpc (Σ 1 ), taking advantage of the Hi spectra stacking technique using both the Arecibo Fast Legacy ALFA Survey and the Sloan Digital Sky Survey. We find that the shapes of M HI -M h and M HI -M * relations are remarkably similar for both star-forming and quenched galaxies, with massive quenched galaxies having constantly lower Hi masses of around 0.6 dex. This similarity strongly suggests that neither halo mass nor stellar mass is the direct cause of quenching, but rather the depletion of Hi reservoir. While the Hi reservoir for low-mass galaxies of M * < 10 10.5 M strongly increases with M h , more massive galaxies show no significant dependence of M HI with M h , indicating the effect of halo to determine the smooth cold gas accretion. We find that the star formation and quenching of central galaxies are directly regulated by the available Hi reservoir, with an average relation of SFR ∝ M 2.75 HI /M 0.40 * , implying a quasi-steady state of star formation. We further confirm that galaxies are depleted of their Hi reservoir once they drop off the star-formation main sequence and there is a very tight and consistent correlation between M HI and Σ 1 in this phase, with M HI ∝ Σ −2 1 . This result is in consistent with the compaction-triggered quenching scenario, with galaxies going through three evolutionary phases of cold gas accretion, compaction and post-compaction, and quenching.

From large-scale environment to CGM angular momentum to star forming activities -- I: star-forming galaxies

“…As can be seen, during its evolution history, this galaxy had move to and fro between star-forming and quenched states multiple times, exhibiting a typical episodic star-formation pattern among star-forming galaxies. It is worth noting that Guo et al (2021) made use of the stacked HI spectra from both the Arecibo Fast Legacy ALFA Survey (ALFALFA; Haynes et al 2018;Jones et al 2018) and the Sloan Digital Sky Survey (Albareti et al 2017) and also discovered an episodic evolution path for the HI gas in the galaxy, which suggests that a galaxy may go through cycles of gas accretion, gas compaction and quenching before being rejuvenated and starting a new episode of star formation, fully in line with this study. We note that, such an episodic behaviour through star-forming and quiescent phases only shows up in the SFR-mass diagram (as presented in Fig.…”