Research Group "Origin and Evolution of Galaxies"

Institut d'Astrophysique de Paris

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Summary of a journal-club Date Subject Presented by 3 september 2009 The Sources of Ionisation for the Gas of Early-type Galaxies: the SAURON Answer The SAURON survey has revealed that down to an detection limit of 0.1A, 75% of early-type galaxies display diffuse ionised-gas emission, which comes with an intriguing variety of spatial distributions, kinematic behaviours, and emission-line ratios. I will investigate the relative role of AGN activity, star-formation, shocks, thermal conduction and photo-ionisation by evolved stars in powering the observed nebular emission of early-type galaxies. Drawing on these results, I will suggest that caution is needed when studying the unresolved nebular emission observed in early-type galaxies through large-scale surveys such as the SDSS survey, in particular when it comes to interpreting AGN activity Marc Sarzi Univ. Herfordshire Image : D1 Deep Field from the Legacy Survey of the Canada-France-Hawaï Telescope (CFHTLS) TERAPIX Data Processing Center (CNRS/INSU - IAP - CEA)