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Cluster Radius

(radius of a galaxy cluster)

A Galaxy Cluster's radius (Cluster Radius) is measured according to various criteria, some based upon the extent of the extra Mass Density (more generally used for Dark Matter Halos). It is a Virial Radius. Some that are used:

Estimated proportions:

R500c:R200c:R200m:Rsp≈1:1.4:3:4

Distant galaxy clusters are often scaled in relation to the critical density at the redshift of the cluster, because there are galaxy cluster attributes that follow that scale. The commonly-used galaxy cluster radius value R500 indicates the radius that surrounds a volume whose mean density is 500 times the critical density at that redshift. Radii within the cluster can be usefully scaled as R/R500.

Values used, based, e.g., on R500:

Other parameters can be defined similarly.


(galaxy clusters,measure,radius)
http://arxiv.org/abs/1504.05591
http://www.physics.utah.edu/snowcluster/talks/nagai.pdf
https://ned.ipac.caltech.edu/level5/Sept09/Bohringer/Bohringer3.html

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