Scientific Seminars

Galaxy and AGN Evolution in the Spitzer Era

Carlotta Gruppioni
INAF - Osservatorio Astronomico di Bologna

2006-10-11    14:00    Brera -

Infrared wavelengths hold the key to understanding the evolution of galaxies, since much of the light emitted by stars is absorbed by dust and re-emitted at mid and far infrared wavelengths. Only by understanding infrared extragalactic populations we can hope to get a reliable census of the star-formation history of galaxies and estimate the fraction of dust-obscured AGN. However, a proper analysis of the evolution of sources emitting in the Infrared is strongly dependent on their broad-band spectral properties (SEDs) at different redshifts and luminosities and on a reliable classification allowing to disentangle AGN from star-formation activity. The diagnostic diagrams based on the optical line ratios are often ambiguous and/or misleading not allowing a proper separation of the galaxy/AGN populations. Thanks to unprecedented depth and the crucial wavelength range of Spitzer (and sometimes the combination with deep X-ray data) a much better census of the hidden AGN activity and dust-obscured star-forming galaxies can be obtained. I will show how to take advantage of the new Spitzer and X-ray survey data to constrain galaxy and AGN evolution in the infrared, revising the results of previous phenomenological models.