Heidelberg Joint Astronomical Colloquium

Speaker Dieter Lutz
Title First results from the Herschel deep extragalactic surveys

ESA's Herschel Space Observatory, launched in May 2009, combines sensitive far-infrared detectors with the large mirror that is necessary to reduce source confusion at these wavelengths. Herschel effectively opens a new window for studying galaxy evolution and unraveling the sources of the cosmic infrared background. I will present first results from the Herschel extragalactic surveys, focussing on deep observations of popular multiwavelength fields obtained at 100 and 160µm. More than half of the cosmic infrared background at these wavelengths is now resolved into individually detected sources whose redshifts and nature can be characterised. Direct calorimetric luminosities and star formation rates can now be measured for many high redshift galaxies, avoiding the uncertainties of extrapolations from shorter or longer wavelengths that were affecting past studies. Herschel data shed new light on the star formation properties of high-z galaxies including AGN hosts and help placing them in the picture combining secular evolution of high redshift galaxies and galaxy mergers.