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Australian Human Resources Institute Diversity Awards 2013 Finalist

Rob Proctor, Brazil ()

"Probing the 2-D kinematic structure of early-type galaxies out to 3 effective radii"

Abstract. I detail an innovative new technique for measuring the 2-D velocitymoments (rotation velocity, velocity dispersion and Gauss-Hermitecoefficients h3 and h4) using spectra from Keck DEIMOSmulti-object spectroscopic observations. The data are used toreconstruct 2-D rotation velocity maps.Here we present data for nearby early-type galaxies to ~3effective radii. From these data 2D kinematic maps are constructed. (see 2009, MNRAS, 398,91). We provide significant insights into the global kinematicstructure of these galaxies, and, in some cases, challenge theaccepted morphological classification. We show that between 1--3effective radii the velocity dispersion declines very slowly, if atall, in all five galaxies. For the two galaxies with velocitydispersion profiles available from planetary nebulae data we find verygood agreement with our stellar profiles. We find a variety ofrotation profiles beyond 1 effective radius, i.e remain constant,decrease emph{and} increase with radius. These results are ofparticular importance to studies which attempt to classify galaxies bytheir kinematic structure within one effective radius, such as therecent definition of fast- and slow- rotator classes by the SAURONproject. Our data suggests that the rotator class may change whenlarger galacto-centric radii are probed. This has importantimplications for dynamical modelling of early-type galaxies. The datafrom this study are available on-line.

Held in the AAO Conference room at 03:30 PM on Thursday, 29 July 2010