# The morphological transformation and the quenching of galaxies

## TL;DR

This study investigates how galaxy morphology transforms and how star formation is quenched, revealing that stellar mass and halo environment significantly influence these processes across different galaxy types.

## Contribution

It provides a detailed analysis of the roles of stellar and halo mass in galaxy transformation and quenching, using SDSS DR7 data and classifying galaxies into four distinct types.

## Key findings

- Morphological transformation mainly depends on stellar mass.
- Quenching is driven by stellar mass in massive galaxies and halo mass in less massive ones.
- Stronger halo quenching effect observed in early type galaxies.

## Abstract

We study the morphological transformation from late types to early types and the quenching of galaxies with the seventh Data Release (DR7) of the Sloan Digital Sky Survey (SDSS). Both early type galaxies and late type galaxies are found to have bimodal distributions on the star formation rate versus stellar mass diagram ($\lg SFR - \lg M_*$). We therefore classify them into four types: the star-forming early types (sEs), the quenched early types (qEs), the star-forming late types (sLs) and the quenched late types (qLs). We checked many parameters on various environmental scales for their potential effects on the quenching rates of late types and early types, as well as the early type fractions among star-forming galaxies and those among quenched galaxies. These parameters include: the stellar mass $M_*$, and the halo mass $M_{halo}$; the small-scale environmental parameters, such as the halo centric radius $R_p/r_{180}$ and the third nearest neighbor distances ($d_{3nn}$); the large-scale environmental parameters, specifically whether they are located in clusters, filaments, sheets, or voids. We found that the morphological transformation is mainly regulated by the stellar mass. Quenching is mainly driven by the stellar mass for more massive galaxies and by the halo mass for galaxies with smaller stellar masses. In addition, we see an overall stronger halo quenching effect in early type galaxies, which might be attributed to their lacking of cold gas or earlier accretion into the massive host halos.