No Evidence for Evolution in the Far-infrared–Radio Correlation out to z ~ 2 in the Extended Chandra Deep Field South

Abstract

We investigate the 70 μm far-infrared-radio correlation (FRC) of star-forming galaxies in the Extended Chandra Deep Field South (ECDFS) out to z > 2. We use 70 μm data from the Far-Infrared Deep Extragalactic Legacy Survey (FIDEL), which comprises the most sensitive (~0.8 mJy rms) and extensive far-infrared deep field observations using MIPS on the Spitzer Space Telescope, and 1.4 GHz radio data (~8 μJy beam^(–1) rms) from the Very Large Array. In order to quantify the evolution of the FRC, we use both survival analysis and stacking techniques, which we find give similar results. We also calculate the FRC using total infrared luminosity and rest-frame radio luminosity, q TIR, and find that q TIR is constant (within 0.22) over the redshift range 0-2. We see no evidence for evolution in the FRC at 70 μm, which is surprising given the many factors that are expected to change this ratio at high redshifts.