Oral Presentation Astronomical Society of Australia Annual Scientific Meeting including HWWS 2013

Globular Cluster Studies Uncover remarkable details of Ongoing Accretion in the Haloes of two nearby Early-type Galaxies (#20)

Christina Blom 1
  1. Swinburne University, Hawthorn, VIC, Australia

It is thought that giant early type galaxies accrete large numbers of smaller galaxies during the later stages of their evolution. Observers have only recently uncovered the low surface brightness light showing these accretion events as they happen. The photometric discoveries of intra-group/intra-cluster light tantalise us with the potential chemical and dynamical information that could be gleaned from spectroscopic observations, but these spectroscopic observations are just out of reach with current instruments. I will discuss how I have used photometric and spectroscopic observations of globular clusters, situated in tidally stripped stellar streams and accreting onto NGC 4365 and NGC 4111, to extract some of the chemical and dynamical details contained in the stellar streams. Globular clusters are much more easily observed than diffuse stellar light and can be used to illuminate the properties of galaxy/group haloes.

    NGC 4365 is a group dominant elliptical galaxy, 6 Mpc behind the Virgo Cluster, showing a number of rare properties, including the combination of a kinematically distinct core and a ~90 degree kinematic misalignment as well as a unique 3rd globular cluster subpopulation. It is currently accreting another strange galaxy NGC 4342, which has itself been the subject of much recent debate regarding its own dark matter halo. NGC 4111 is an S0 galaxy, also the dominant member of a group 15 Mpc away and we have discovered a stellar stream extending from another group galaxy UGC 7094 to the centre of NGC 4111. I will present results from wide-field imaging and state-of-the-art spectroscopy from the DEep Imaging Multi-Object Spectrograph (DEIMOS) on the Keck II telescope.