Ultra Deep Catalogue of Galaxy Structures in the COSMOS field

COLDWELL, GEORGINA; ILONA SOECHTING; ROGER CLOWES ; LUIS CAMPUSANO; MATTHEW GRAHAM

Buenos Aires

Workshop; Second Workshop on Numerical and Observational Astrophysics: From the First Structures to the Universe Today; 2011

Institute for Astronomy and Space Physics (IAFE)

We present a large sample of intermediate to high redshift galaxy groups and clusters detected in the COSMOS field. The fully automated detection algorithm is based on density peak extraction from a density distribution sampled using Voronoi tessellation within overlapping slices in the photometric redshift space. The  catalogue contains 1780 structures covering the redshift range of 0.2 to 3.0, spanning three orders of magnitude in luminosity and richness from eight to hundreds of galaxies. The redshift distribution of detected structures shows strong variations with prominent peaks suggesting the presence of large scale structures such as supercluster candidates. The identification of a compact agglomeration of galaxy groups and clusters  at z = 2.9 propose the presence of a supercluster which would be the highest redshift candidate so far. Nevertheless, all clusters at z > 0.4 and many even below this threshold show very prominent substructure suggesting that z ∼ 0.4 marks the slow emergence of virialized clusters in this field.