A search for super-large structures in deep galaxy surveys

Abstract

Recent extensive, multi-color deep surveys of galaxies open a possibility to get observational estimation of sizes for the largest structures in the Universe. Photometric redshift accuracy (about 0.03(1+z)) allows directly study clustering at scales about 1000 Mpc. Thanks to large number of galaxies in each redshift bin one may detect super-large structures if they really exist. Here we show that the observed behavior of the redshift distribution of galaxies in deep surveys such as HUDF and FDF is consistent with existence of super-large structures of luminous matter with scales about 2000 Mpc. We detect a large underdense region in radial galaxy distribution at redshift interval z=1.2 - 2.2 which separate our "Local Hubble Volume" from the neighboring over-density region at z=2.2 - 3.5. This result can also explain the observed deficiency of gamma ray sources at redshift about 2. Observational test on the reality of the supper-large structures may be obtained by organizing sky covering net (cells about 10n x 10n degrees) of very deep narrow angle (1n x 1n arc-minutes) multi-band photometric surveys of galaxies which is achievable for large ground-based telescopes.