English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We examine the origins of the bimodality observed in the global properties ofgalaxies around a stellar mass of 3x10^10 M_sun by comparing the environmentaldependencies of star-formation for the giant and dwarf galaxy populations. TheSloan Digital Sky Survey DR4 spectroscopic dataset is used to produce a sampleof galaxies in the vicinity of the supercluster centered on the cluster A2199at z=0.03 that is ~90% complete to a magnitude limit of M*+3.3. From these wemeasure global trends with environment for both giant (M_r<-20 mag) and dwarf(-19<M_r<-17.8 mag) subsamples using the luminosity-weighted mean stellar ageand H_alpha emission as independent measures of star-formation history. Thefraction of giant galaxies classed as old (t>7 Gyr) or passive (EW[H_alpha]<4A) falls gradually from ~80% in the cluster cores to ~40% in field regionsbeyond 3-4 R_virial, as found in previous studies. In contrast, we find thatthe dwarf galaxy population shows a sharp transition at ~1 R_virial, from beingpredominantly old/passive within the cluster, to outside where virtually allgalaxies are forming stars and old/passive galaxies are only found assatellites to more massive galaxies. These results imply fundamentaldifferences in the evolution of giant and dwarf galaxies: whereas thestar-formation histories of giant galaxies are determined primarily by theirmerger history, star-formation in dwarf galaxies is much more resilient to theeffects of major mergers. Instead dwarf galaxies become passive only once theybecome satellites within a more massive halo, by losing their halo gasreservoir to the host halo, or through other environment-related processes suchas galaxy harassment and/or ram-pressure stripping.Comment: 4 pages, 4 figures, accepted for publication in ApJ

The Different Environmental Dependencies of Star Formation for Giant and Dwarf Galaxies