81 research outputs found
The Evolution of galaxies in clusters. 5. A Study of populations since Z approximately equal to 0.5
The evolution of the colors of cluster galaxies since redshift of about 0.5 is studied using photometry of 33 clusters. In each cluster, those galaxies brighter than M(v) = -20 which are within the circular area containing the inner 30 percent of the total cluster population are selected. From the distribution of these galaxies in the color-magnitude plane, the fraction of galaxies whose rest-frame B-V colors are at least 0.2 mag bluer than the ridge line of the early-type galaxies at that magnitude is determined. It is found that low-redshift compact clusters form a very homogeneous group of objects with cores essentially devoid of blue galaxies. At redshifts greater than 0.1, compact clusters have significant numbers of blue galaxies, the fraction increasing with redshift. The colors of spiral galaxies in the cores of nearby clusters tend to be redder than those of spirals in the fiel
The Concentration-Density Relation of Galaxies in Las Campanas Redshift Survey
We report the results of the evaluation of the ``concentration-density''
relation of galaxies in the local universe, taking advantage of the very large
and homogeneous data set available from the Las Campanas Redshift Survey
(Shectman et al. 1996). This data set consists of galaxies inhabiting the
entire range of galactic environments, from the sparsest field to the densest
clusters, thus allowing us to study environmental variations without combining
multiple data sets with inhomogeneous characteristics. Concentration is
quantified by the automatically-measured concentration index , which is a
good measure of a galaxy's bulge-to-disk ratio. The environment of the sample
galaxies is characterized both by the three-space local galaxy density and by
membership in groups and clusters. We find that the distribution of C in galaxy
populations varies both with local density and with cluster/group membership:
the fraction of centrally-concentrated galaxies increases with local galaxy
density, and is higher in clusters than in the field. A comparison of the
concentration-local density relation in clusters and the field shows that the
two connect rather smoothly at the intermediate density regime, implying that
the apparent cluster/field difference is only a manifestation of the variation
with the local density. We conclude that the structure of galaxies is
predominantly influenced by the local density and not by the broader
environments characterized by cluster/field memberships.Comment: 11 pages, 4 figures, ApJ in press, uses psfig.st
The Luminosity Function of Galaxies in the Las Campanas Redshift Survey
We present the -band luminosity function for a sample of 18678 galaxies,
with average redshift , from the Las Campanas Redshift Survey. The
luminosity function may be fit by a Schechter function with , , and $\phi^* = 0.019 \pm 0.001 \
h^3^{-3}-23.0 \leq M - 5 \log h \leq -17.5b_J \approx 20b_J \approx 20\alpha = -0.7\alpha = -1W_{\lambda} = 5\alphaM^* =
-20.03 \pm 0.03 + 5 \log h\alpha = -0.9 \pm 0.1M^* = -20.22 \pm 0.02 + 5 \log h\alpha = -0.3
\pm 0.1$.
(abridged abstract)Comment: 41 pages, including 13 postscript figures, uses AASTEX v4.0 style
files. Important clarification of R-band definition, plus correction of
luminosity densities and updated references. Main conclusions unchanged.
Final version to appear in Ap
The Texture of the Universea a
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71428/1/j.1749-6632.1984.tb23343.x.pd
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