CURRENT PROJECTS

 

GALAXY AND MASS ASSEMBLY SURVEY (GAMA)
with Andrew Hopkins (AAO), Simon Driver (University of Western Australia) and the GAMA team.

GAMA public website

Using the AAOmega multi-fibre spectrograph on the Anglo-Australian Telescope (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:

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.


BRIGHTEST CLUSTER GALAXY EVOLUTION: PhD student Paola Oliva-Altamirano (Swinburne University) has been leading research into the growth in stellar mass of the most massive galaxies in the GAMA sample.  She has found no evidence for their growth over the last 3 billion years (Oliva-Altamirano, Brough et al., submitted) which contradicts suggestions from models that they should have increased in mass by a factor ~1.4.


IFU FOLLOW-UP: Limitations of current research into galaxy evolution stem from a lack of spatially-resolved spectroscopy. Large surveys use a single optical fibre 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 have led a project observing GAMA galaxies with the SPIRAL IFU on the AAT to determine the effects of environment on the radial distributions of galaxies.  We found no significant dependence of the distribution of star formation on environment (Brough et al. 2013).

SAMI SURVEY

with Scott Croom (University of Sydney) and the SAMI team.


SAMI survey public website

Using the SAMI (Sydney-AAO Multi-object Integral field spectrograph; Croom et al. 2012) instrument on the AAT to conduct the largest integral field survey of 3000 galaxies to determine how their spatial properties (star formation and kinematic morphology, amongst others) depend on environment and stellar mass.  SAMI will revolutionise the future of galaxy evolution research!

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 the Sloan Digital Sky Survey (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 (1:1.5 and 1:1.3) companions are likely to merge with their host BCGs in 0.35 Gyr in major, dry mergers. I conclude that BCGs do 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 at Texas A&M University has analysed more data from the VLT, confirming this picture. He also found that above Dynamical Mass ~11.5 (log solar mass) all galaxies have low angular momentum (
Jimmy et al. 2013).  PhD student Paola Oliva-Altamirano (Swinburne University) will measure the stellar population gradients of this expanded sample to determine their star formation histories.

WiggleZ DARK ENERGY SURVEY

with Chris Blake, Warrick Couch, Karl Glazebrook (Swinburne) and the WiggleZ team.


WiggleZ public website

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.