The Aquarius Superclusters

Collaborators: C.A. Caretta (MAST/MCT), C.N.A. Willmer (UCO/Lick), W. Kawasaki (UTokio)

Two of the three richest second order clusterings in Abell's list named SC-16 and SC-17, are found in the region of Aquarius constellation (the third being Cor-Bor, SC-13). They are contained in an area of about 10o X 6o. We intended to examine the cluster distribution and the superclusters membership. This project also was the subject of CÚsar A. Caretta MSc and PhD.  Thus, we had somebody to help us with the hard labor.

We were stimulated by the possibility that these two superclusters could take part of a single structure with approximately 200 Mpc or more as suggested by preliminary cluster redshift measurements. We obtained ESO Schmidt plates for that region, that were digitized by APM machine. Spectroscopic observations were carried out in telescopes of ESO (1.52m) in Chile, LNA/MCT (1.6m) in Brazil, and CASLEO (2.15m) in Argentina.

The major findings are that we have in this region 63 clusters already known and 39 new candidate clusters identified using matched-filter technique and counts in cells analysis. The projected cluster distribution can be seen in the figure below.

 

Using a percolation radius of 10Mpc (spatial density contrast about 10), we detect 2 superclusters  of galaxies in Aquarius, at z ~ 0.086 and 0.112, respectively with 5 and 14 clusters. In the figure below, we display the cone diagram for the distribution of 56 rich clusters (squares), and 53 poor clusters or groups (triangles and crosses). Concentrations at z ~0.08 and 0.11 are easily seen, as well as a chain of clusters from 0.11 to 0.14.

 

Our data support the interpretation that the Z~0.11 supercluster in Aquarius is very significant concentration of matter, representing a density contrast ~160 and a mass of at least 1016 solar masses. Those results above and many others are presented in the paper by Caretta et al. (2002).

Attention ! The catalog containing spectroscopic and photometric data for the Aquarius galaxies is available here.

The Doctor thesis of C. Caretta (in portuguese ) is available in PDF format (pdf file 7.65Mby).