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Australian Human Resources Institute Diversity Awards 2013 Finalist

Paola Oliva (Swinburne University)

"Brightest group and cluster galaxies as proves of galaxy formation"

Abstract. Brightest group and cluster galaxies (BGGs/BCGs) are old giant elliptical, which have been show to be different from any other cluster galaxy. Despite of being easy detectable their formation and evolution is still poorly understood.

I will present a statistical analysis of growth, position, star formation, and AGN activity, of a large sample of 883 BGGs/BCGs from the Galaxy and Mass Assembly Survey (GAMA). In the last 3 billion years we find no significant growth in these extremely massive galaxies. We also find that around 13 per cent of the BGGs/BCGs are not lying at the centre of the dark matter halo potential well, being an indicator of recent cluster mergers. We further find that approximately 65 per cent of BGGs/BCGs show H\alpha line emission, and at least 30 per cent of the BGGs/BCGs harbour on-going star formation and another 30 per cent are AGNs. BGGs are more likely to be star forming, while BCGs show little to non star formations. This is visible through the Star Formation Rate (SFR) - stellar mass relation. The SFR seems to decrease with stellar mass, and have an efficiency peak in galaxies of around 10^{10.8}M$\odot$.

However, mergers have been found to be responsible of the BGGs/BCGs growth since z=1, in this talk I will discuss the connection between angular momentum and merger rates in BCGs. We analyse the spatially resolved stellar kinematics in 10 BCGs with companions observed with VIMOS in IFU mode. The results are compared with the galaxies of the SAURON and ATLAS^{3D} projects.

Held in the AAO Meeting Room (Room 7, 1st Floor, Building 2) at 11:00 AM on Friday, 04 October 2013