H$\alpha$-based Star Formation Rates in and around z $\sim$ 0.5 EDisCS clusters

TL;DR

This study examines how environment influences star formation in galaxies at z~0.5 using Hα emission, finding little dependence on environment for star formation rates in massive galaxies, with some galaxies showing signs of quenching.

Contribution

First to analyze Hα-based star formation rates across different environments in z~0.5 clusters, highlighting the potential rapid quenching process.

Findings

Star formation rates show little dependence on environment for massive galaxies.

Hα-based star formation rates are consistent with other studies at similar redshifts.

Some galaxies with Hα emission are UVJ-quiescent, indicating ongoing quenching.

Abstract

We investigate the role of environment on star-formation rates of galaxies at various cosmic densities in well-studied clusters. We present the star-forming main sequence for 163 galaxies in four EDisCS clusters in the range 0.4 $<$ z $<$ 0.7. We use {\em Hubble Space Telescope}/Wide Field Camera 3 observations of the H$\alpha$ emission line to span three distinct local environments: the cluster core, infall region, and external field galaxies. The main sequence defined from our observations is consistent with other published H$\alpha$ distributions at similar redshifts, but differs from those derived from star-formation tracers such as 24$\mu$m. We find that the H$\alpha$-derived star-formation rates for the 67 galaxies with stellar masses greater than the mass-completeness limit of M$_*>$ 10$^{9.75}$M\textsubscript{\(\odot\)} show little dependence on environment. At face value, the similarities in the star-formation rate distributions in the three environments may indicate that the process of finally shutting down star formation is rapid, however, the depth of our data and size of our sample make it difficult to conclusively test this scenario. Despite having significant H$\alpha$ emission, 21 galaxies are classified as {\em UVJ}-quiescent and may represent a demonstration of the quenching of star formation caught in the act.