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Title

Eridanus: a supergroup in the local universe?

Author(s)

Brough, Sarah;  Forbes, Duncan A.;  Kilborn, Virginia A.;  Couch, Warrick;  Colless, Matthew

Abstract

We examine a possible supergroup in the direction of the Eridanus constellation using 6dF Galaxy Survey second data release (6dFGS DR2) positions and velocities together with Two-Micron All-Sky Survey and Hyper-Lyon-Meudon Extragalactic DAtabase photometry. We perform a friends-of-friends analysis to determine which galaxies are associated with each substructure before examining the properties of the constituent galaxies. The overall structure is made up of three individual groups that are likely to merge to form a cluster of mass . We conclude that this structure is a supergroup. We also examine the colours, morphologies and luminosities of the galaxies in the region with respect to their local projected surface density. We find that the colours of the galaxies redden with increasing density, the median luminosities are brighter with increasing environmental density and the morphologies of the galaxies show a strong morphology-density relation. The colours and luminosities of the galaxies in the supergroup are already similar to those of galaxies in clusters; however, the supergroup contains more late-type galaxies, consistent with its lower projected surface density. Due to the velocity dispersion of the groups in the supergroup, which are lower than those of clusters, we conclude that the properties of the constituent galaxies are likely to be a result of merging or strangulation processes in groups outlying this structure.

Publication type

Journal article

Research centre

Swinburne University of Technology. Faculty of Information and Communication Technologies. Centre for Astrophysics and Supercomputing

Source

Monthly Notices of the Royal Astronomical Society, Vol. 369, no. 3 (2006), p. 1351-1374

Publication year

2006

Keyword(s)

Galaxy clusters;  Galaxy evolution;  Galaxies;  NGC 1332;  NGC 1395;  NGC 1407;  Surveys

Publisher

Blackwell Publishing

ISSN

0035-8711

Publisher URL

http://dx.doi.org/10.1111/j.1365-2966.2006.10387.x

Copyright

Copyright © 2006 Royal Astronomical Society. Author's final draft reproduced here on 08 January 2009 in accordance with the copyright policy of the publisher.

Full text

Peer reviewed