AAS 205th Meeting, 9-13 January 2005
Session 94 From Protogalaxies to Large Surveys: Tracing the Galaxy Evolution
Poster, Wednesday, January 12, 2005, 9:20am-6:30pm, Exhibit Hall

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[94.16] Searching for Variability in the Hubble Ultra Deep Field: Clues to Galaxy Mergers.

S. H. Cohen, R. E. Ryan, A. N. Straughn, N. P. Hathi, R. A. Windhorst (Arizona State University), A. M. Koekemoer, N. Pirzkal, C. Xu, B. Mobasher, J. E. Rhoads, S. Malhotra, L. G. Strolger (STScI)

The Hubble Ultra Deep Field was observed over a period of four months. We searched through the data in the i' and z' bands to find variable sources. The data was broken into 4 epochs of approximately equal exposure time, and photometry was performed in matched apertures defined from the full depth UDF images. The observed photometric error distribution between epochs is modelled and 3-4\sigma outliers are selected as candidates. We are searching for optical or rest-frame UV variability most likely due to AGN activity in the galaxies or perhaps the merging of two galaxies containing AGN. The statistics and photometric redshift distribution of the variable sources will be discussed in the context of galaxy mergers. With similar photometric stability and proper planning, this method could be used to find higher redshift galaxy mergers and/or AGN with JWST. This work is supported by HST grants AR10298.* and GO 9793.*, and NASA JWST grant NAG 5-12460.

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© 2004. The American Astronomical Society.