AAS 195th Meeting, January 2000
Session 10. Multiwavelength Observations of Clusters of Galaxies
Display, Wednesday, January 12, 2000, 9:20am-6:30pm, Grand Hall

[Previous] | [Session 10] | [Next]

[10.10] Searching for Young S0 Galaxies in Abell 2052

D.H. McIntosh (Steward Obs.), H.-W. Rix (MPIA), N. Caldwell (SAO)

Numerous studies have established strong observational evidence for evolution in cluster member color and morphology. Such evolution is predicted by hierarchical structure formation scenarios where galaxy clusters evolve via accretion of mass from the field. It has been hypothesized that recently accreted large surface brightness spirals will rapidly evolve via some star formation (SF) truncation mechanism into smooth disk galaxies with little or no current SF, but relatively young stellar populations. These younger S0's (hereafter bluer S0's = BS0's) would have bluer colors than the older early-types (E/S0) that define the mean cluster color-magnitude relation (CMR). The existence of such galaxies provides explanations for the disappearance of the blue, star-forming disk galaxies that were common in clusters at z~0.5 (the Butcher-Oemler effect), and the increased fraction of S0's in present-day clusters. To date a significant population of BS0's in nearby clusters has not been found. Therefore, we have obtained wide field (R > 0.6 Mpc), high precision UVI photometry for a sample of 14 local (z < 0.06) Abell clusters, most with over <100 spectroscopically confirmed members.

We present photometric results for our first completely reduced cluster, Abell 2052. We have selected candidate BS0's as those early-type members that deviate blueward from the CMR by more than the intrinsic CMR scatter. We used 2-D bulge/disk (B/D) decomposition as an indicator of morphology to refine our sample. This spring, we will obtain spectroscopy of this sample to confirm the relative youth of the stellar populations. In addition, we will use the B/D decompositions of these candidate BS0's to address the following questions: (1) do BS0's make up a significant fraction of the early-type members that deviated from the cluster mean CMR; (2) do BS0's avoid the inner cluster; (3) are BS0's bluer in their disks or bulges; (4) do BS0's exhibit a range of B/D ratios similar to that found in field Sb-Sd galaxies. Answers to these questions will help determine important cluster evolution issues such as which of the various theoretical mechanisms (galaxy harassment, spiral mergers, ram pressure stripping, etc.) provide the dominate source of SF truncation.

The author(s) of this abstract have provided an email address for comments about the abstract: dmac@slayer.as.arizona.edu

[Previous] | [Session 10] | [Next]