Spitzer Survey of the Large Magellanic Cloud: Surveying the Agents of a Galaxy?s Evolution (SAGE). I. Overview and Initial Results

Abstract

We are performing a uniform and unbiased imaging survey of the Large Magellanic Cloud (LMC; ~7 deg ×7 deg) using the IRAC (3.6, 4.5, 5.8, and 8 μm) and MIPS (24, 70, and 160 μm) instruments on board the Spitzer Space Telescope in the Surveying the Agents of a Galaxy's Evolution (SAGE) survey, these agents being the interstellar medium (ISM) and stars in the LMC. This paper provides an overview of the SAGE Legacy project, including observing strategy, data processing, and initial results. Three key science goals determined the coverage and depth of the survey. The detection of diffuse ISM with column densities >1.2×10 21 H cm -2 permits detailed studies of dust processes in the ISM. SAGE's point-source sensitivity enables a complete census of newly formed stars with masses >3 M solar that will determine the current star formation rate in the LMC. SAGE's detection of evolved stars with mass-loss rates >1×10 -8 M solar yr -1 will quantify the rate at which evolved stars inject mass into the ISM of the LMC. The observing strategy includes two epochs