AEGIS20: a radio survey of the Extended Groth Strip

Abstract

We describe AEGIS20 - a radio survey of the Extended Groth Strip (EGS) conducted with the Very Large Array (VLA) at 1.4GHz. The resulting catalog contains 1,123 emitters and is sensitive to ultraluminous 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 uJy-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, SFRD, rises by at least ~5x from z=0-1, 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 (AGN) comes at the price of rejecting luminous starbursts. Whilst 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.