The SAMI galaxy survey: bulge and disk properties of cluster galaxies

ABSTRACT:   The formation of lenticular galaxies is still a deep mystery and conflicting results are found in the literature regarding their origin: Johnston et al. (2014) observed younger stellar populations in bulges of cluster lenticular galaxies than those in the disks, while Head et al. (2014) observed that the bulges are generally older than the disk components. The method used by Johnston et al. (2014) consists of decomposing long-slit spectroscopic data to build separated one-dimensional spectra of the bulge and the disk, while Head et al. (2014) performed 2D photometric bulge-disk decomposition in multiple bands and analysed the colours. In this context, the study of more than 800 cluster galaxies from the Sydney-AAO Multi-Object Integral field spectrograph (SAMI) galaxy survey offers a unique tool to resolve these discrepancies between the results and the methods. SAMI allows to combine the 2D photometric bulge-disk decomposition, performed in the g-, r- and i-bands using the new analysis packages ProFound and ProFit, with the information from the integral field spectroscopic data. In this talk, I will explain how disentangling the ages and metallicities of bulge and disk stellar populations sheds light on galaxy evolution and I will show some important preliminary findings.