Photometric Objects Around Cosmic Webs (PAC). VII. Disentangling Mass and Environment Quenching with the Aid of Galaxy–Halo Connection in Simulations

Abstract

Star formation quenching in galaxies plays a crucial role in galaxy evolution and is believed to be driven primarily by galaxy mass and environment. However, disentangling these effects is difficult because galaxy mass and environment are strongly correlated. In Paper V, we addressed this challenge using the Photometric Objects Around Cosmic Webs method, which integrates spectroscopic and deep photometric surveys. This approach enabled us to measure the excess surface density ${\bar{n}}_{2}{w}_{{\rm{p}}}({r}_{{\rm{p}}})$ of blue and red galaxies surrounding massive central galaxies down to 10 ^9.0 M _⊙ . Despite this, fully separating mass and environmental effects remains challenging due to the difficulty in identifying a complete sample of low-mass central galaxies in redshift space. To overcome this, we derive the average quenched fraction of central galaxies, ${\bar{f}}_{{\rm{q}}}^{{\rm{cen}}}({M}_{* })$ , by combining the reconstructed 3D quenched fraction distribution ${f}_{{\rm{q}}}^{{\rm{sat}}}(r;{M}_{* ,{\rm{cen}}},{M}_{* ,{\rm{sat}}})$ , the stellar mass-halo mass relation in simulations, and the observed total quenched fraction, ${\bar{f}}_{{\rm{q}}}^{{\rm{all}}}({M}_{* })$ . With ${\bar{f}}_{{\rm{q}}}^{{\rm{cen}}}({M}_{* })$ , ${f}_{{\rm{q}}}^{{\rm{sat}}}(r;{M}_{* ,{\rm{cen}}},{M}_{* ,{\rm{sat}}})$ and the galaxy–halo connection, we assign a quenched probability to each (sub)halo and analyze galaxy quenching comprehensively. Our findings indicate that mass quenching dominates, with the mass-quenched fraction increasing from 0.3 to 0.87 across the stellar mass range [10 ^9.5 , 10 ^11.0 ] M _⊙ , while environmental quenching decreases from 0.17 to 0.03. Furthermore, more massive host halos are more effective at quenching their satellite galaxies, whereas satellite stellar mass has a minimal impact on environmental quenching. Within the studied stellar mass range, TNG300-1 exhibits lower mass-quenching efficiency but higher environmental-quenching compared to observations.

Keywords

• Galaxy evolution
• Galaxy formation
• Galaxy quenching