Please note this talk has been canceled.

Abstract:

I present a new study of M31’s structure and stellar populations from a map of the M31 bulge and disk out to R=40 kpc in ugriJKs bands. The CFHT Andromeda Optical & Infrared Disk Survey (ANDROIDS) can uniquely observe both resolved stars and integrated spectral energy distributions (SEDs) over M31’s entire disk (complementing HST’s PHAT program). By simultaneously fitting star formation histories from the color-magnitude diagrams of stars and the panchromatic SEDs of pixels, ANDROIDS can test systematic biases of SED modelling. Photometric background calibration across the 5-gigapixel map is a substantial challenge for this work. A hierarchical Bayesian model simultaneously constrains the photometric background in each band while modelling the star formation history in all pixels across M31. 2D maps of M31’s stellar mass-to-light ratio (M/L), age and metallicity are presented.  Panchromatic SED modelling is shown to be essential even for stellar mass estimation, let alone age and metallicity.