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

UV Strong Red Sequence Cluster Galaxies: Their Environment and Morphology. (#76)

Jacob P Crossett 1 , Kevin A Pimbblet 1 , John P Stott 2 , Heath Jones 1
  1. Monash University, Clayton, Vic, Australia
  2. School of Physics, University of Durham, Durham City, United Kingdom

While it is commonly accepted that most spheroidal galaxies on the red sequence contain largely older stellar populations, it has been suggested that a small amount of recent star formation may have occurred within the last billion years. This residual star formation is observationally determined by high NUV flux, and is found to be present in over 10% of early-type galaxies down of a magnitude of R=-18 in five massive clusters from the Las Campanas/AAO Rich Cluster Survey at z~0.1. I will present results usingĀ  Galex NUV-R colour magnitude diagrams to determine the broad morphological and environmental properties of these galaxies with this residual star formation to explain their formation. I will show that despite optical colours corresponding to the red sequence, these galaxies are not found to resemble early-type galaxies, but reside in low density (~100 Gal/Mpc2) at predominantly high (>2Mpc) radii from their host cluster centre. In addition to this, their morphology portrays a low concentration, Sersic index=1 profile. This suggests evidence of "quenching" of star formation in late type galaxies, as opposed to a residual burst of star formation.