NOAO >   Observing Info >   Approved Programs >   2004A-0228

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Proposal Information for 2004A-0228


PI: Ana Matkovic, University of Florida, matkovic@astro.ufl.edu
Address: Department of Astronomy, 211 Bryant Space Science Center BOX 112055, Gainesville, FL 32611

CoI: Rafael Guzman, University of Florida

Title: Testing The Galaxy Harassment Scenario for The Formation of Cluster Dwarf Ellipticals

Abstract: The 'galaxy harassment' model offers an explanation of how the dwarf spiral galaxies in distant clusters, due to encounters with brighter galaxies and the cluster's tidal field, have evolved into today's population of cluster dwarf ellipticals (dEs). We propose to test this model by comparing the metallicity and kinematics of dEs located in the inner and outer regions of the Coma cluster. The model predicts that, on average, dEs located in the inner, high-density cluster regions should be more metallic and have larger velocity dispersions than those in the outer regions. However, no such differences have yet been observed due to a lack of statistically representative sample of cluster dEs that include velocity dispersions and metallicities. To date there are only ~70 dEs known with these properties, including our sample of ~50 from the inner 1^\circ region of the Coma cluster. In 2003 we were able to obtain new spectra for ~25 of the brightest dEs (b<1! 8.0) in the outskirts of the Coma cluster, using WIYN/HYDRA. However, it is essential to have kinematic and metallicity measurements of dEs with a wide luminosity range for both the inner and outer parts of the cluster in order to test the galaxy harassment model. Therefore, we propose to complete measurements of our outskirts sample by obtaining spectra of ~50 dEs spanning the same range in luminosity (17.4<b<20.4 mag) as the already observed inner cluster sample.


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