Richness distribution of string-seeded Abell clusters - Accretion by a loop versus hierarchical clustering

Abstract

view Abstract Citations (7) References (36) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Richness Distribution of String-seeded Abell Clusters: Accretion by a Loop versus Hierarchical Clustering Zurek, W. H. Abstract We discuss formation of objects around loops of cosmic string in an Einstein-de Sitter universe dominated by either cold or hot dark matter. In particular, we solve, in the Zeldovich approximation, the problem of accretion of cold dark matter onto a stationary point mass introduced into the universe either in radiation or matter-dominated epoch. This process can be used to model formation of Abell clusters around loops of cosmic string. Predicted distribution of masses of Abell clusters is consistent with the observed richness distribution only when the loops seeding clusters of richness 1 enter the horizon at about the time when accretion can begin in earnest, that is, just before t_eq_. The formation epoch is also consistent with Abell cluster separations and with the estimates of their masses, provided that the dimensionless string tension is of the order of 10^-6^. If the loops were laid down much earlier, or if-as could be the case in the universe with the sufficiently hot dark matter-accretion could not start until some time after they were deposited, supermassive Abell clusters would be more common than observed. Loops laid down too late (t>=3t_eq_) yield, on the other hand, richness distribution far too steep to explain observations. We also estimate mass distribution of Abell clusters in hierarchical clustering models: It reproduces observations especially well when the power spectrum on the Abell cluster scales is close to that of white noise. Publication: The Astrophysical Journal Pub Date: January 1988 DOI: 10.1086/165877 Bibcode: 1988ApJ...324...19Z Keywords: Astronomical Models; Dark Matter; Galactic Clusters; Galactic Evolution; Mass Distribution; String Theory; Big Bang Cosmology; Hierarchies; Loops; Universe; White Noise; Astrophysics; COSMOLOGY; DARK MATTER; GALAXIES: CLUSTERING; GALAXIES: FORMATION full text sources ADS |