THE GRISM LENS-AMPLIFIED SURVEY FROM SPACE (GLASS). VII. THE DIVERSITY OF THE DISTRIBUTION OF STAR FORMATION IN CLUSTER AND FIELD GALAXIES AT 0.3 <= z <= 0.7
2016
ASTROPHYSICAL JOURNAL
DOI
10.3847/1538-4357/833/2/178
Exploiting the slitless spectroscopy taken as part of the Grism Lens-Amplified Survey from Space (GLASS), we present an extended analysis of the spatial distribution of star formation in 76 galaxies in 10 clusters at 0.3 < z < 0.7. We use 85 foreground and background galaxies in the same redshift range as a field sample. The samples are well matched in stellar mass (10(8)-10(11) M-circle dot) and star formation rate (0.550 M-circle dot yr(-1)). We visually classify galaxies in terms of broad band morphology, Ha morphology, and likely physical process acting on the galaxy. Most Ha emitters have a spiral morphology (41% +/- 8% in clusters, 51% +/- 8% in the field), followed by mergers/interactions (28% +/- 8%, 31% +/- 7%, respectively) and early-type galaxies (remarkably as high as 29% +/- 8% in clusters and 15% +/- 6% in the field). A diversity of Ha morphologies is detected, suggesting a diversity of physical processes. In clusters, 30% +/- 8% of the galaxies present a regular morphology, mostly consistent with star formation diffused uniformly across the stellar population (mostly in the disk component, when present). The second most common morphology (28% +/- 8%) is asymmetric/jellyfish, consistent with ram-pressure stripping or other non-gravitational processes in 18% +/- 8% of the cases. Ram-pressure stripping appears significantly less prominent in the field (2% +/- 2%), where the most common morphology/mechanism appears to be consistent with minor gas-rich mergers or clump accretion. This work demonstrates that while environment-specific mechanisms affect galaxy evolution at this redshift, they are diverse and their effects are subtle. A full understanding of this complexity requires larger samples and detailed and spatially resolved physical models.