The Structure of Clusters of Galaxies and the Angular Size-Redshift Test

Citation

Hickson, Paul (1976) The Structure of Clusters of Galaxies and the Angular Size-Redshift Test. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/6F00-K950. https://resolver.caltech.edu/CaltechETD:etd-09022008-152652

Abstract

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. An angular size-redshift cosmological test is presented based on the projected separations between bright cluster galaxies as the size statistic. The method is applied to 95 clusters of galaxies with redshifts ranging from .02 to .46 yielding a value of the deceleration parameter before evolution of q[...] = -.9. After correcting for known evolutionary effects we obtain q[...] = -.8. The formal standard deviation in q[...] at these values is .2, which corresponds to an uncertainty of about .4 at q[...] = 0. It is argued that the selection criteria for the sample, and the observed behavior of the cluster size dispersion with redshift precludes the existence of any major selection or evolutionary effects in the data. Structure parameters are presented for a sample of 64 cosmologically near clusters, and correlated with Rood and Sastry type. New type classifications are presented for 23 clusters. Mean surface density profiles are determined for the various cluster types. It is found that many clusters are deficient in separations of one to two Mpc.

Thesis Files