The Structure of the Coma Cluster of Galaxies

Citation

Noonan, Thomas Wyatt (1961) The Structure of the Coma Cluster of Galaxies. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/QCN1-K914. https://resolver.caltech.edu/CaltechETD:etd-04072006-094220

Abstract

In a re-interpretation of Zwicky's Coma-cluster counts, the brighter and fainter galaxies have nearly identical distributions, and the cluster covers an area approximately 3°20' in diameter. There are approximately 1560 members to the limit, of the 48-inch Schmidt telescope. Zwicky's data are consistent with a recent survey of the Coma cluster by Abell. The observed counts closely resemble the distribution of matter in an isothermal gas sphere. Any method for computing the mass which uses the structure of the isothermal gas sphere is equivalent to applying the virial theorem. The virial-theorem mass based on latest available data is 2 x 10(15) [solar masses]. It is not difficult for a non-equilibrium model to have a distribution similar to the isothermal gas sphere. The hypothesis that the Coma cluster is a young cluster is consistent with the observed spatial distribution and colors of the galaxies. The age could be as short as 2 x 10(9) years, and the "hidden mass" could be in the unseen parts of galaxies still evolving.

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