1993/05/14 by Tsvi Piran, T. Piran, M. Lecar +11
Physics and Astronomy · #Astrophysics (astro-ph) #Cosmology and Gravitation Theories #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #Scientific Research and Discoveries #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9305019
23 pages, tex, 1 figure can be obtaine from [email protected] CFA-3640
openalex publication_date 1993/05/14 · arxiv created 1993/05/17 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We suggest to use the common appearance of voids with a scale of 5000 \kms in the galaxy distribution to estimate the power spectrum on this scale. We use a simple model for a gravitational formation of voids and we compare the results with the matter fluctuations as constrained by the CMBR observations of COBE. We find that a power spectrum P(k)∝ kn with n ≈ 1.25 is compatible both with COBE and with gravitational growth of large voids in an Ω=1 universe. A Harrison-Zel'dovich spectrum, n=1, normalized to produce the observed CMBR fluctuations, does not have enough power for gravitational growth of voids with a diameter of 5000 \kms in an Ω=1 Universe. Such a spectrum would be compatible if (i) void diameters are smaller (3500 \kms), the voids are shallower or if the voids are rare (we assume that the universe is void filled); (ii) Ω< 1 i.e. the Universe is open; (iii) galaxies do not trace matter on very large scale or if (iv) the voids do not grow gravitationally.