arXiv subjects

Christopher J. Miller

Publications and source records attributed to Christopher J. Miller.

77 records · Page 5Linked to original sources

arXiv2001

The Power Spectrum of Rich Clusters on Near Gigaparsec Scales

Recently, there have been numerous analyses of the redshift space power spectrum of rich clusters of galaxies. Some of these analyses indicate a "bump" in the Abell/ACO cluster power spectrum around k= 0.05hMpc^-1. Such a feature in the power spectrum excludes most standard formation models and indicates possible periodicity in the distribution of large-scale structure. However, the data used in detecting this peak include clusters with estimated redshifts and/or clusters outside of Abell's (1958) statistical sample, i.e. R=0 clusters. Here, we present estimations of the redshift-space power spectrum for a newly expanded sample of 637 R >= 1 Abell/ACO clusters which has a constant number density to z = 0.10 in the Southern Hemisphere and a nearly constant number density to z = 0.14 in the Northern Hemisphere. The volume sampled, \~10^8h^{-3}Mpc^{3}, is large enough to accurately calculate the power per mode to scales approaching 10^3h^{-1}Mpc. We find the shape of the power spectrum is is a power-law on scales 0.02 <= k <= 0.10hMpc^{-1}, with enhanced power over less rare clusters, such as APM clusters. The slope of this power-law is n= -1.4. The power spectrum is essentially featureless, although we do see a dip near $k = 0.04h$Mpc$^{-1}$ which cannot be considered statistically significant based on this data alone. We do not detect a narrow peak at $k \sim 0.05h$Mpc$^{-1}$ and there is no evidence for a turn-over in the power spectrum as has been previously reported. We compare the shape of the Abell/ACO rich cluster power spectrum to various linear models.

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arXiv2000

Einstein Cluster Alignments Revisited

We have examined whether the major axes of rich galaxy clusters tend to point toward their nearest neighboring cluster. We have used the data of Ulmer, McMillan, and Kowalski, who used position angles based on X-ray morphology. We also studied a subset of this sample with updated positions and distances from the MX Northern Abell Cluster Survey (for rich clusters ($R \geq 1$) with well known redshifts). A Kolmogorov-Smirnov (KS) test showed no significant signal for nonrandom angles on any scale $\leq 100h^{-1}$Mpc. However, refining the null hypothesis with the Wilcoxon rank-sum test, we found a high confidence signal for alignment. Confidence levels increase to a high of 99.997% as only near neighbors which are very close are considered. We conclude there is a strong alignment signal in the data, consistent with gravitational instability acting on Gaussian perturbations.

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arXiv1999

Wavelength Doesn't Matter: Optical vs. X-ray Luminosities of Galaxy Clusters

We examine the relationship between the total X-ray and optical luminosities of groups and clusters of galaxies taken from various samples in the literature. The clusters and groups were drawn from four different catalogs: (1) the Abell/ACO catalog, (2) the Edinburgh-Durham Cluster Catalog, (3) the RASS Bright Cluster Sample, and (4) galaxy groups selected from the CfA redshift survey. These catalogs represent a significant cross-section of cluster selection tchniques as well as a wide range in mass scale and can be considered statistically independent. We have calculated new cluster X-ray and optical luminosities if not available in the literature. Based on 126 systems, our analysis shows that the total optical luminosity of a cluster is directly proportional to the total X-ray luminosity over a wide mass range and across all four cluster samples studied herein. We also show that total cluster optical luminosity is a good indicator of cluster virial mass, but richness is not. Our results suggest that (1) the selection method of galaxy clusters may not be crucial, providing wider latitude in assembling catalogs, (2) the luminosity per baryon does not vary systematically between systems ranging from groups to very rich clusters. We propose that future optical catalogs of clusters use the total optical luminosity of a cluster, instead of galaxy richness, as luminosity appears to be a better measure of cluster mass and can be directly related to X-ray catalogs of clusters. This will also facilitate the first direct comparison between the growing number of X-ray and optical catalogs.

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arXiv1999

Environmental Dependence of the Fundamental Plane of Galaxy Clusters

Galaxy clusters approximate a planar (FP) distribution in a three-dimensional parameter space which can be characterized by optical luminosity, half-light radius, and X-ray luminosity. Using a high-quality catalog of cluster redshifts, we find the nearest neighbor cluster for those common to an FP study and the cluster catalog. Examining scatter about the FP, we find 99.2% confidence that it is dependent on nearest neighbor distance. Our study of X-Ray clusters finds that those with high central gas densities are systematically closer to neighbor clusters. If we combine results here with those of Fritsch and Buchert, we find an explanation for some of our previous conclusions: Clusters in close proximity to other clusters are more likely to have massive cooling flows because they are more relaxed and have higher central gas densities.

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arXiv1999

Massive Cooling Flow Clusters Inhabit Crowded Environments

With the availability of large-scale redshift survey data, it is now becoming possible to explore correlations between large-scale structure and the properties and morphologies of galaxy clusters. We investigate the spatial distributions of a 98% complete, volume-limited sample of nearby (z<0.1) Abell clusters with well-determined redshifts and find that cooling flow clusters with high mass-accretion rates have nearest neighbors which are much closer than those of other clusters in the sample (at the 99.8% confidence level), and reside in more crowded environments out to 30/h Mpc. Several possible explanations of this effect are discussed.

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