# The time delay between star formation quenching and morphological transformation of galaxies in clusters: a phase-space view of EDisCS

## TL;DR

This study investigates how cluster environments influence galaxy structure and star formation histories at intermediate redshifts by analyzing phase-space positions, structural deviations, and stellar ages, revealing that galaxy transformation occurs gradually within clusters.

## Contribution

It introduces a phase-space analysis linking galaxy positions, structures, and stellar ages, highlighting the gradual nature of galaxy transformation in clusters at intermediate redshifts.

## Key findings

- Younger star-forming galaxies are rougher and more asymmetric.
- Galaxy stellar ages correlate with their phase-space positions.
- Structural parameters do not strongly segregate with phase-space position.

## Abstract

We explore the possible effect of cluster environments on the structure and star formation histories of galaxies by analysing the projected phase-space (PPS) of intermediate-redshift cluster (0.4<z<0.8). HST I-band imaging data from the ESO Distant Cluster Survey (EDisCS) allow us to measure deviations of the galaxies' light distributions from symmetric and smooth profiles using two parameters, Ares ('asymmetry') and RFF (residual flux fraction or 'roughness'). Combining these structural parameters with age-sensitive spectral indicators like Hdelta, Hgamma and Dn4000, we establish that in all environments younger star-forming galaxies of all morphologies are 'rougher' and more asymmetric than older, more quiescent ones. Combining a subset of the EDisCS clusters we construct a stacked PPS diagram and find a significant correlation between the position of the galaxies on the PPS and their stellar ages, irrespective of their morphology. We also observe an increasing fraction of galaxies with older stellar populations towards the cluster core, while the galaxies' structural parameters (Ares and RFF) do not seem to segregate strongly with PPS. These results may imply that, transformation happens on a longer timescale as they accumulate and age in the cluster cores.