Superclusters and Large Scale Structure


Over the past few years my collaborators Todd Small (Caltech), Don Hamilton (University of Munich) and I carried out two large galaxy redshift surveys with the Norris Multifiber Spectrograph on the 200 inch Hale Telescope at the Palomar Observatory . The Norris Spectrograph can obtain the spectra of up to 176 objects simultaneously over a 22 arc minute field. We have surveyed fields in the direction of the Corona Borealis Supercluster and areas around the isolated cluster Abell 104. Chung-Pei Ma (University of Pennsylvania), has used her expertise in n-body simulations of cosmological structures to help interpret our data.


The above plot shows the redshift distribution of about 1400 galaxies in the field of Abell 104. The prominent peak at z ~ 0.08 is due to Abell 104 itself. Emission line galaxies are coloured blue and early type galaxies are colored red. The plot clearly illustrates the well known tendency for early type galaxies to be more clustered than late type galaxies.


A redshift "pie" diagram for the Abell 104 region is shown above. It was devised by Todd Small who, like me, believes that none of the galaxies in this or any other region of the universe has even one team as boring as Arsenal. The concentration of galaxies around the redshift of Abell 104 (z ~0.08) is clearly visible. The lozenge shape of the galaxy redshift distribution is due to the large virial velocities within the cluster. The different colors show galaxy groupings inferred using a "friends of friends" algorithm.
Some of our papers on the Norris Surveys:


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page by Wallace Sargent, last updated 15 December 1999