Measuring galaxy environments with deep redshift surveys

Michael C. Cooper, Jeffrey A. Newman, Darren S. Madowick, Brian F. Gerke, Renbin Yan, Marc Davis

Research output: Contribution to journalArticlepeer-review

121 Scopus citations

Abstract

We study the applicability of several galaxy environment measures (nth-nearest neighbor distance, counts in an aperture, and Voronoi volume) within deep redshift surveys. Mock galaxy catalogs are employed to mimic representative photometric and spectroscopic surveys at high redshift (z ∼ 1). We investigate the effects of survey edges, redshift precision, redshift-space distortions, and target selection on each environment measure. We find that even optimistic photometric redshift errors (σz = 0.02) smear out the line-of-sight galaxy distribution irretrievably on small scales; this significantly limits the application of photometric redshift surveys to environment studies. Edges and holes in a survey field dramatically affect the estimation of environment, with the impact of edge effects depending on the adopted environment measure. These edge effects considerably limit the usefulness of smaller survey fields (e.g., the GOODS fields) for studies of galaxy environment. In even the poorest groups and clusters, redshift-space distortions limit the effectiveness of each environment statistic; measuring density in projection (e.g., using counts in a cylindrical aperture or a projected nth-nearest neighbor distance measure) significantly improves the accuracy of measures in such overdense environments. For the DEEP2 Galaxy Redshift Survey, we conclude that among the environment estimators tested the projected nth-nearest neighbor distance measure provides the most accurate estimate of local galaxy density over a continuous and broad range of scales.

Original languageEnglish
Pages (from-to)833-848
Number of pages16
JournalAstrophysical Journal
Volume634
Issue number2 I
DOIs
StatePublished - Dec 1 2005

Keywords

  • Galaxies: high-redshift
  • Galaxies: statistics
  • Large-scale structure of universe
  • Methods: data analysis
  • Methods: statistical
  • Surveys

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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