期刊
ASTROPHYSICAL JOURNAL LETTERS
卷 816, 期 2, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.3847/2041-8205/816/2/L25
关键词
galaxies: clusters: general; galaxies: evolution; galaxies: formation; galaxies: star formation
资金
- PRIN-INAF
- Fondazione Ing. Aldo Gini
- World Premier International Research Center Initiative (WPI), MEXT, Japan
- Kakenhi from the Japan Society for the Promotion of Science (JSPS) [26870140]
The star formation quenching depends on environment, but a full understanding of what mechanisms drive it is still missing. Exploiting a sample of galaxies with masses M-* > 10(9.8) M-circle dot, drawn from the WIde-field Nearby Galaxy-cluster Survey (WINGS) and its recent extension OMEGAWINGS, we investigate the star formation rate (SFR) as a function of stellar mass (M-*) in galaxy clusters at 0.04 < z < 0.07. We use non-member galaxies at 0.02 < z < 0.09 as a field control sample. Overall, we find agreement between the SFR-M-* relation in the two environments, but detect a population of cluster galaxies with reduced SFRs, which is rare in the field. These transition galaxies are mainly found within the cluster virial radius (R-200), but they impact on the SFR-M-* relation only within 0.6R(200). The ratio of transition to pure star-forming galaxies strongly depends on environment, being larger than 0.6 within 0.3R(200) and rapidly decreasing with distance, while it is almost flat with M-*. As galaxies move downward from the SFR-M-* main sequence, they become redder and present older luminosity-and mass-weighted ages. These trends, together with the analysis of the star formation histories, suggest that transition galaxies have had a reduced SFR for the past 2-5 Gyr. Our results are consistent with the hypothesis that the interaction of galaxies with the intracluster medium via strangulation causes a gradual shut down of star formation, giving birth to an evolved population of galaxies in transition from being star forming to becoming passive.
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