2007ApJ...660L..77I

We describe AEGIS20–a radio survey of the Extended Groth Strip (EGS) conducted with the Very Large Array (VLA) at 1.4 GHz. The resulting catalog contains 1123 emitters and is sensitive to ultraluminous (10¹² L_☉) starbursts to z≤1.3, well matched to the redshift range of the DEEP2 spectroscopic survey in this region. We use stacking techniques to explore the microjansky-level emission from a variety of galaxy populations selected via conventional criteria–Lyman break galaxies (LBGs), distant red galaxies (DRGs), UV-selected galaxies, and extremely red objects (EROs)–determining their properties as a function of color, magnitude, and redshift and their extinction-free contributions to the history of star formation. We confirm the familiar pattern that the star formation rate (SFR) density, ρ_*, increases by at least a factor of ∼5 from z = 0 to 1, although we note highly discrepant UV- and radio-based SFR estimates. Our radio-based SFRs become more difficult to interpret at z>1 where correcting for contamination by radio-loud active galactic nuclei (AGNs) comes at the price of rejecting luminous starbursts. While stacking radio images is a useful technique, accurate radio-based SFRs for z≫1 galaxies require precise redshifts and extraordinarily high fidelity radio data to identify and remove accretion-related emission.