Clusters of galaxies are a cornerstone of modern cosmology. Wide-ranging studies of clusters reaching from the nearby universe to large redshift provide constraints on the growth of structure in the universe and on the cosmological parameters.

HeCS (Hectospec Cluster Survey) is the largest survey to date of clusters in the redshift range z = 0.1-0.3. The survey includes a total of 22,680 redshifts in the fields of 58 clusters. The redshift surveys include 10,145 cluster members (paper reference). Rines et al. (2013) includes on-line data tables for the entire survey.

In the redshift range of the HeCS clusters. the 1circ field of the Hectospec (LINK) covers both the virialized central regions of the clusters and the surrounding infall regions. The display below of a subset of the clusters in redshift space reveals the expected trumpet-shaped patterns.


The amount of matter within the solid lines provides a good estimate of the ultimate mass the clusters will have in the far future of the universe. Rines et al. (2013) estimate these ultimate masses and find that they agree with theoretical predictions.

Simulations of the growth of clusters of galaxies generally show them in real physical space (configuration space) rather than in the redshift space where we observe them. The plot below shows the difference between real space and redshift space. In redshift space the trumpet-shaped patterns appear.

Watching the development of clusters in real space and in redshift space provides a fascinating view of the limits to our understanding of these systems imposed by our limited view and by the limited number of objects we can observe in any given system.


We have extended HeCS to include a dense survey of the strong lensing cluster Abell 383 (reference). IMAGE of A383?