CURRENT PROJECTS
MERGING HISTORY AND STELLAR KINEMATICS OF BRIGHTEST CLUSTER GALAXIES (BCGs)
with Kim-Vy Tran (Texas A&M), Rob Sharp (Mount Stromlo), Anja von der Linden (Stanford), Warrick Couch (Swinburne).
We have used the VIMOS Integral Field Unit (IFU) on the VLT to examine BCGs selected from Sloan (von der Linden et al. 2007) with visually determined companions, or with no discernable features (the control sample) to examine the merging in these massive galaxies that are predicted to have undergone significant numbers of recent mergers (Brough et al. 2011b). I have shown that while the BCG with a low mass companion (1:4) is not bound, the two BCGs with nearly equal mass (1:1.45 and 1:1.25) companions are likely to merge with their host BCGs in 0.35 Gyr in major, dry mergers. I conclude that BCGs continue to grow from major merging even in the local Universe. Analysing the stellar kinematics we find that not all these massive galaxies have low angular momentum as one might expect. One of the four BCGs and the two massive companions are found to be fast-rotating galaxies with high angular momentum, thereby providing a new test for models of galaxy evolution and the formation of Intra-Cluster Light.
PhD student Jimmy Erickson at Texas A&M is analysing more data from the VLT to build on this kinematic analysis. PhD student Paola Oliva at Swinburne University will measure the stellar population gradients of this expanded sample to determine their star formation histories.
GALAXY EVOLUTION WITH THE GALAXY AND MASS ASSEMBLY SURVEY (GAMA)
with Andrew Hopkins (AAO), Simon Driver (UWA) and the GAMA team.
Using the AAOmega multi-fibre spectrograph on the AAT to measure the distances of galaxies to z~0.4. With this high fidelity, large area, multi-wavelength (X-ray, UltraViolet, Optical Imaging and Spectra, Near infrared, Radio) survey I am leading the following projects:
LITTLE BLUE FUZZIES: I have recently finished the analysis of the lowest star forming galaxies in the GAMA survey (Brough et al. 2011a) which I find to be generally small, low-mass, star-forming galaxies. I conclude that these galaxies have current specific star formation rates consistent with their having had a variety of star formation histories and that they are found to exist predominantly in the lowest density environments. The low density environments demonstrates that such low-mass, star-forming systems can only remain as low-mass and forming stars if they reside sufficiently far from other galaxies to avoid being accreted, dispersed through tidal effects or having their gas reservoirs rendered ineffective through external processes.
ENVIRONMENTS: I am leading the analysis of different metrics of galaxy environment measured for the GAMA survey - examining how the different metrics affect the results obtained and the conclusions drawn.
IFU FOLLOW-UP: Limitations of current research into galaxy evolution stem from a lack of spatially resolved spectroscopy. Large surveys use a single optical fibre per galaxy, typically sampling less than half the light from a galaxy. These surveys cannot measure crucial spatially dependent observables such as the location of star formation as well as age and metallicity gradients. Kinematic information providing dynamical mass and evidence of mergers is also impossible to extract. I am leading a project to observe GAMA galaxies with the SPIRAL IFU on the AAT to determine the effects of environment on the radial distributions of galaxies.
SAMI SURVEY
with Scott Croom (University of Sydney) and the SAMI team.
Using the prototype SAMI (Sydney AAO Multi-IFU; Croom et al. 2012) integral field unit on the AAT to conduct one of the largest integral field surveys of galaxies to determine how their spatial properties depend on environment and stellar mass.
WiggleZ DARK ENERGY SURVEY
with Chris Blake, Warrick Couch, Karl Glazebrook (Swinburne) and the WiggleZ team.
Using the AAOmega multi-fibre spectrograph on the AAT to measure the baryon acoustic oscillations and calculate the ratio of the dark energy pressure and density [w(z)] at z~0.8, i.e. the expansion rate of the distant universe, using a sample of ~200,000 emission-line galaxies over 1000 square degrees.