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 μm of the SCUBA submillimeter sources and μJy 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 ( L IR > 10 11 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.