Abstract
ABSTRACT We investigate the role of environment on star formation rates (SFRs) 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 Hubble Space Telescope/Wide Field Camera 3 observations of the H α 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 α distributions at similar redshifts but differs from those derived from star formation tracers such as 24 $\, \mu$m. We find that the Hα-derived SFRs for the 67 galaxies with stellar masses greater than the mass-completeness limit of M* > 109.75 M⊙ show little dependence on environment. At face value, the similarities in the SFR 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 α emission, 21 galaxies are classified as UVJ-quiescent and may represent a demonstration of the quenching of star formation caught in the act.
Highlights
Star formation governs the conversion of a galaxy’s gas into stars and is characterized by the balance of cold gas accretion and feedback (Boucheet al. 2010; Dutton et al 2010)
We explore the environmental dependence of spectroscopically derived H α star formation in three distinct regimes in the vicinity of four galaxy clusters at 0.4 < z < 0.7: cluster cores, infall regions, and the field
We combine Hubble Space Telescope (HST)/Wide Field Camera 3 (WFC3) G102 grism observations at 1 μm with photometric and spectroscopic redshift priors to obtain a sample of 67 galaxies with secure redshifts, S/N in H α > 3 and which are above our mass completeness limit for star-forming galaxies of M∗ > 109.75
Summary
Star formation governs the conversion of a galaxy’s gas into stars and is characterized by the balance of cold gas accretion and feedback (Boucheet al. 2010; Dutton et al 2010). While the main sequence is generally presented with a slope ranging from 0.2 to 1.2 (Speagle et al 2014), there have been numerous studies that show that bulge-dominated massive galaxies contribute towards a flattening in the star formation rate (SFR) at higher masses (Karim et al 2011; Whitaker et al 2012, 2014; Schreiber et al 2015; Erfanianfar et al 2016) This ‘internal’ quenching mechanism is directly related to the morphology of the galaxy and results in a less efficient conversion of gas to stars (Martig et al 2009). The overall observed scatter in the main sequence is likely due to varying star formation histories of each galaxy (Domınguez Sanchez et al 2014; Hopkins et al 2014), where this scatter is consistent across stellar mass and redshift at ∼ 0.3 dex (Whitaker et al 2012; Tacchella et al 2016)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
