Abstract
We analyze GALEX UV data for a system of four gravitationally-bound groups at z=0.37, SG1120, which is destined to merge into a Coma-mass cluster by z=0, to study how galaxy properties may change during cluster assembly. Of the 38 visually-classified S0 galaxies, with masses ranging from log(M_*)~10-11, we detect only one in the NUV channel, a strongly star-forming S0 that is the brightest UV source with a measured redshift placing it in SG1120. Stacking the undetected S0 galaxies (which generally lie on or near the optical red-sequence of SG1120) still results in no NUV/FUV detection (<2 sigma). Using our limit in the NUV band, we conclude that for a rapidly truncating star formation rate, star formation ceased *at least* ~0.1 to 0.7 Gyr ago, depending on the strength of the starburst prior to truncation. With an exponentially declining star-formation history over a range of time-scales, we rule out recent star-formation over a wide range of ages. We conclude that if S0 formation involves significant star formation, it occurred well before the groups were in this current pre-assembly phase. As such, it seems that S0 formation is even more likely to be predominantly occurring outside of the cluster environment.
Sign-in/Register to access full text options 
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 callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
