  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,
star-forming 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, 8 microns and MIPS 24, 70, 160 microns. The Legacy Extragalactic
Catalog may contain in excess of 2 million IR-selected galaxies, dominated by
(1) ~150,000 luminous infrared galaxies (LIRGs: L{FIR}>10^11 L_sun), ~7000 of
these with z>2; (2) 1 million early-type galaxies, ~10,000 with z>2; and (3)
\~20,000 classical AGN, 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. SWIRE's large area is important to create statistically
significant population samples over enough volume cells that we can resolve the
star formation history as a function of epoch and environment The large volume
is also optimised for finding rare objects.
