SWIRE: The SIRTF Wide-area InfraRed Extragalactic Survey

The SIRTF Wide-area InfraRed Extragalactic survey (SWIRE), the largest SIRTF Legacy program, is a wide-area, imaging survey to trace the evolution of dusty, starforming galaxies, evolved stellar populations, and AGN as a function of environment, from redshifts z∼3 to the current epoch. SWIRE will survey 7 high-latitude fields, totaling 60 65 sq. deg. in all 7 SIRTF bands: IRAC 3.6, 4.5, 5.6, 8μm and MIPS 24, 70, 160μm. Extensive modeling suggests that the Legacy Extragalactic Catalog may contain in excess of 2 million IR-selected galaxies, dominated by (1) ∼150,000 luminous infrared galaxies (LIRGs: LFIR > 10 11 L⊙) detected by MIPS (and significantly more detected by IRAC), ∼7,000 of these with z>2; (2) 1 million IRAC-detected early-type galaxies (∼ 2×105 with z > 1 and ∼10,000 with z > 2); and (3) ∼ 20,000 classical AGN detected with MIPS, plus significantly more dust-obscured QSO/AGN among the LIRGs. SWIRE will provide an unprecedented view of the evolution of galaxies, structure, and AGN. The key scientific goals of SWIRE are: (1) to determine the evolution of actively star-forming and passively evolving galaxies in order to understand the history of galaxy formation in the context of cosmic structure formation; (2) to determine the evolution of the spatial distribution and clustering of evolved galaxies, starbursts and AGN in the key redshift range, 0.5<z<3, over which much of cosmic evolution has occurred; (3) to determine the evolutionary relationship between “normal galaxies” and AGN, and the contribution of AGN accretion energy vs. stellar nucleosynthesis to the cosmic backgrounds. The large area of SWIRE is important to establish statistically significant population samples over enough volume cells that we can resolve the star formation history as a function of epoch and environment, i.e. in the context of structure formation. The large volume is also optimised for finding rare objects. The SWIRE fields are likely to become the next generation of large “Cosmic Windows” into the extragalactic sky. They have been uniquely selected to minimize Galactic cirrus emission over large scales. GALEX will observe them as part of its deep 100 sq deg survey, as will Herschel. SWIRE includes ∼9 sq deg of the unique large-area XMMLSS hard X-ray imaging survey, and is partly covered by the UKIDSS deep J & K survey. An extensive optical/near-IR imaging program is underway from the ground. The SWIRE data are non-proprietary; catalogs and images will be released twiceyearly, beginning about 11 months after SIRTF launch. Details of the data products and release schedule are presented. Subject headings: surveys – galaxies: evolution – galaxies: active – large-scale structure