# The SAMI Galaxy Survey: Satellite galaxies undergo little structural change during their quenching phase

## TL;DR

This study shows that satellite galaxies experience minimal structural change during quenching, with star formation rates decreasing more significantly than stellar spin, which mainly reflects progenitor bias rather than environmental effects.

## Contribution

It provides observational and simulation evidence that satellite quenching involves little change in stellar spin, emphasizing the role of progenitor bias over environmental effects.

## Key findings

- Satellites have lower SFR and spin than centrals at fixed mass.
- Most spin decrease occurs after satellites reach the red sequence.
- Spin differences are mainly due to progenitor bias, not environmental effects.

## Abstract

At fixed stellar mass, satellite galaxies show higher passive fractions than centrals, suggesting that environment is directly quenching their star formation. Here, we investigate whether satellite quenching is accompanied by changes in stellar spin (quantified by the ratio of the rotational to dispersion velocity V/$\sigma$) for a sample of massive ($M_{*}>$10$^{10}$ M$_{\odot}$) satellite galaxies extracted from the SAMI Galaxy Survey. These systems are carefully matched to a control sample of main sequence, high $V/\sigma$ central galaxies. As expected, at fixed stellar mass and ellipticity, satellites have lower star formation rate (SFR) and spin than the control centrals. However, most of the difference is in SFR, whereas the spin decreases significantly only for satellites that have already reached the red sequence. We perform a similar analysis for galaxies in the EAGLE hydro-dynamical simulation and recover differences in both SFR and spin similar to those observed in SAMI. However, when EAGLE satellites are matched to their `true' central progenitors, the change in spin is further reduced and galaxies mainly show a decrease in SFR during their satellite phase. The difference in spin observed between satellites and centrals at $z\sim$0 is primarily due to the fact that satellites do not grow their angular momentum as fast as centrals after accreting into bigger halos, not to a reduction of $V/\sigma$ due to environmental effects. Our findings highlight the effect of progenitor bias in our understanding of galaxy transformation and they suggest that satellites undergo little structural change before and during their quenching phase.