Spitzer Space Telescope - Legacy General Observer Proposal #30948 A Deep-Wide Far-Infrared Survey of Cosmological Star Formation and AGN Activity Principal Investigator: Mark Dickinson Institution: NOAO Co-Investigators: David Frayer, Spitzer Science Center David Alexander, Cambridge University Eric Bell, Max-Planck-Institute for Astronomy, Heidelberg Niel Brandt, Penn State University Daniela Calzetti, Space Telescope Science Institute Scott Chapman, California Institute of Technology Stefano Casertano, Space Telescope Science Institute Ranga-Ram Chary, Spitzer Science Center Emanuele Daddi, National Optical Astronomy Observatory Mark Davis, University of California, Berkeley Hervé Dole, Institut d'Astrophysique Spatiale, Université Pari James Dunlop, University of Edinburgh Peter Eisenhardt, Jet Propulsion Laboratory David Elbaz, CEA Saclay Sandra Faber, University of California Santa Cruz Giovanni Fazio, Smithsonian Astrophysical Observatory Henry Ferguson, Space Telescope Science Institute Mauro Giavalisco, Space Telescope Science Institute Mark Halpern, University of British Columbia Jiasheng Huang, Smithsonian Astrophysical Observatory Minh Huynh, Spitzer Science Center Rob Ivison, Royal Observatory Edinburgh Anton Koekemoer, Space Telescope Science Institute Emeric Le Floc'h, University of Arizona Glenn Morrison, Canada France Hawaii Telescope Leonidas Moustakas, Jet Propulsion Laboratory Casey Papovich, University of Arizona Alexandra Pope, University of British Columbia Alvio Renzini, Padova University George Rieke, University of Arizona Hans-Walter Rix, Max-Planck-Institute for Astronomy, Heidelberg Douglas Scott, University of British Columbia Ian Smail, Durham University Haojing Yan, Spitzer Science Center Pieter van Dokkum, Yale University Paul van der Werf, Leiden Observatory Science Category: high-z galaxies (z>0.5) Observing Modes: MipsPhot MipsScan Hours Approved: 397.0 Abstract: Spitzer is creating a vast legacy of 24 micron imaging, with hundreds of thousands of sources detected at cosmological distances. In principle, 24 micron data are the most sensitive probe of dust-enshrouded star formation and distant active galactic nuclei. In practice, at z > 1, they sample mid-infrared wavelengths complex in structure (PAH emission and silicate absorption) and physics (PAH excitation, metallicity dependence, extinction, warm dust and hidden AGN). Other data are needed to understand MIR emission, to calibrate its relation to star formation, to establish its dependence on other galaxy properties, to measure how many atypical objects there are, and to learn how to account for them in conclusions drawn from deep surveys. We propose a program of very deep MIPS imaging geared toward 70 micron detection of 1000 "normal" IR-luminous galaxies at 0.5 < z < 2.5 at wavelengths which trace thermal dust emission which more directly correlates with physical properties of interest such as star formation rates. We will survey 2200 square arcmin in three premier deep survey fields using far-infrared, radio and submillimeter data to measure bolometric luminosities, dust temperatures and masses, to quantify the population of Compton-obscured AGN, and to calibrate the use of 24 micron data for studying high redshift galaxy evolution.