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The Norris survey of the Corona Borealis supercluster

Citation

Small, Todd Andrew (1996) The Norris survey of the Corona Borealis supercluster. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-09102008-111656

Abstract

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.

We describe the design, construction, and first results of the Norris Survey of the Corona Borealis Supercluster, a redshift survey of a 6[...] x 6[...] region in the core of the Corona Borealis supercluster.

The redshift survey has been conducted with the 176-fiber Norris Spectrograph on the Hale 5m telescope. The input catalog is based on machine scans of Schmidt plates and consists of over 5 x 10[...] objects calibrated in the Gunn g and r bands. We chose to observe 36 20' diameter fields arranged in a 6 x 6 grid across the core of the supercluster. We have completed observations of 23 of these fields, plus an additional 9 fields which were closely spaced along the ridge of galaxies between Abell 2061 and Abell 2067. We have measured redshifts for 1491 extragalactic objects, 420 with [...] 8[...] resolution and the remainder with [...] 4[...] resolution. Our newly measured redshifts were augmented with 163 from the literature, yielding 1654 redshifts for the entire survey. The faintest galaxies in the survey have magnitudes of [...] 22.5[...], and the most distant galaxies have redshifts of [...] 0.7.

We have measured an unexpectedly small number of redshifts (528) in the Corona Borealis supercluster since the supercluster is not as dense as originally believed and since a background supercluster at [...] 0.11 makes a substantial contribution to the projected surface density of galaxies. Despite the small number of redshifts for galaxies in the supercluster, we are able to draw the following conclusions about the dynamics and structure of the Corona Borealis supercluster. (1) The galaxy distribution within the supercluster is far from smooth. The galaxy density falls rapidly away from the Abell cluster cores. (2) The virial mass of the supercluster is [...], which yields a B band mass-to-light ratio of [...]. (3) The dynamics of the supercluster, as revealed through an analysis of the two-point correlation function, suggest that the supercluster has not yet generated large mean flows towards itself and that, therefore, the supercluster has only recently begun to break away from the Hubble expansion.

Since the sample of redshifts extends to z = 0.5, we have been able to investigate the evolution of large-scale structure and of the galaxy population. By computing the projected two-point spatial correlation function [...], we have measured the correlation length [...] and the power-law index [...] of the real space correlation function [...] as a function of redshift. We find that the correlation length declines dramatically with increasing redshift. Incorporating measurements of [...] from other surveys, we measure the evolutionary parameter [...] to be 2.25 [...] 0.1 for [...] = 1.7, well in excess of the linear theory prediction [...] = [...] - 1. We do not see evolution in the clustering of red galaxies; the clustering evolution is limited to the blue galaxies.

We have also measured the pairwise velocity dispersion [...] on a scale of [...] Mpc through an analysis of the two-point spatial correlation function computed as a function of pair separations along and perpendicular to the line-of-sight. Although [...] is quite sensitive to the treatment of rich clusters in the survey, we conclude that [...] is significantly larger than the canonical value of 340 [...] 40 [...] computed by Davis and Peebles (1983). This result is in accord with other recent estimates of [...].

We have characterized structure on scales of [...] Mpc by measuring the one-dimensional power spectrum of our survey. We measure a significant peak on scales of [...] Mpc. The structures responsible for the peak are readily identifiable in redshift-right- ascension cone diagrams: superclusters are separated by large underdense regions.

Using 598 field galaxies with [...] from our survey, we have computed the field galaxy luminosity function as a function of color and redshift. We find compelling evidence that the B band field galaxy luminosity function evolves with redshift. The evolution is limited to blue galaxies; the red galaxies show no sign of change to z = 0.5. The evolution of the luminosity function of blue galaxies, which is corroborated by a [...] test, is reflected in the blueward shift of the median galaxy color with redshift and in the increasing fraction of galaxies displaying the star-formation indicators [0 II] and [...] with redshift.

Item Type:Thesis (Dissertation (Ph.D.))
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Astronomy
Thesis Availability:Restricted to Caltech community only
Research Advisor(s):
  • Sargent, Wallace L. W.
Thesis Committee:
  • Unknown, Unknown
Defense Date:6 December 1995
Record Number:CaltechETD:etd-09102008-111656
Persistent URL:http://resolver.caltech.edu/CaltechETD:etd-09102008-111656
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:3441
Collection:CaltechTHESIS
Deposited By: Imported from ETD-db
Deposited On:26 Sep 2008
Last Modified:26 Dec 2012 02:59

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