Ph.D. Description

H. Patrick Murphy
(Now Patrick P. Murphy)

Awarded January 1983 by

The National University of Ireland

A comparison of Optical and X-ray properties of Selected Clusters of Galaxies
N.A. Porter, University College, Dublin (National University of Ireland)
P.A. Wayman, Dunsink Observatory, Dublin Institute for Advanced Studies
T.C. Weekes, Smithsonian Astrophysical Observatory ( F.L. Whipple Obs., Tucson)
CCD Cameras are used to investigate the optical properties of clusters of galaxies in the context of their X-ray properties and appearance. A new cluster classification based on both optical and X-ray appearance (the Forman-Jones scheme) is discussed in the light of the new CCD observations. The properties of the CCD cameras used are investigated and described, and the suitability of this device for extragalactic research is reviewed. The optical study is reported in two parts. Firstly, the brightest member galaxies in 35 rich Abell clusters were observed and analysed, resulting in confirmation of the known small dispersion in Magnitudes of these objects, and the possibility of a relation between X-ray and optical luminosity. Secondly, detailed observations were made in two colours of the X-ray emitting regions of three clusters at different evolutionary stages. These observations indicate general agreement with the new classification scheme but some discrepancies were found. The central regions of the unevolved cluster A262 have a very high galaxy density, and the evolved cluster A85 is shown to have a peculiar colour distribution. These discoveries indicate a need for more detailed observations.

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