AAS 198th Meeting, June 2001
Session 7. Clusters of Galaxies and Large Scale Structure
Display, Monday, June 4, 2001, 9:20am-6:30pm, Exhibit Hall

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[7.02] Detecting Voids in Galaxy Redshift Surveys

F. Hoyle, M. Vogeley (Drexel University)

Voids are one of the most striking features in any redshift galaxy surveys, however, as yet they have not been extensively studied. This is due to several observational limitations, perhaps the most problematic being that voids are seen to be ~50h-1Mpc in diameter which approaches the characteristic depth of most redshift surveys. This means that there are only of order 10 voids in the current galaxy redshift surveys. Also, voids are very low density objects so observing any objects that reside in them is challenging.

The next generation of redshift surveys (SDSS, 2dF) will improve things in two ways. The surveys will extend to greater depths, allowing a more statistically complete sample to be obtained and the accompanying digital imaging surveys will provide accurate photometry of fainter objects than previous surveys. This will allow us to gain a greater insight into the nature of voids, determine their emptiness, look at properties of void galaxies and perhaps maybe place constraints on cosmology.

The first step in studying voids is the identification process. In this poster we outline a method for detecting voids (which is based on the method of El-Ad and Piran 96). We apply it to two redshift surveys, the CfA survey (Huchra et al. 1995) and the PSCz survey (Saunders et al. 2000), which is the largest completed redshift survey to date. We discuss the results from these surveys and discuss our detection algorithms usefulness for future surveys.

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