SPITZER OBSERVATIONS OF THE SCUBA/VLA SOURCES IN THE LOCKMAN HOLE: STAR FORMATION HISTORY OF INFRARED-LUMINOUS GALAXIES

We present Spitzer Space Telescope imaging observations at 3.6, 4.5, 5.8, 8.0, and 24 ?m of the SCUBA submillimeter sources and ?Jy VLA radio sources in a 5' ? 5' area in the Lockman Hole East region. Out of the ~40 SCUBA/VLA sources in the field, Spitzer counterparts were detected for nearly all except for the few low-weight SCUBA detections. We show that the majority (80%-90%) of the detected sources are cold (i.e., starburst-like) infrared-luminous galaxies (LIR > 1011 L?) at redshift 0.5 < z < 3.5, whose star-formation rate density (SFRD) is comparable to that of the optically selected star-forming galaxies.

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