Evolution of the Far-Infrared-Radio Correlation and Infrared SEDs of
  Massive Galaxies over z = 0 - 2
  We investigate the far-infrared-radio correlation (FRC) of
stellar-mass-selected galaxies in the Extended Chandra Deep Field South using
far-infrared imaging from Spitzer and radio imaging from the Very Large Array
and Giant Metre-Wave Radio Telescope. We stack in redshift bins to probe
galaxies below the noise and confusion limits. Radio fluxes are K-corrected
using observed flux ratios, leading to tentative evidence for an evolution in
spectral index. We compare spectral energy distribution (SED) templates of
local galaxies for K-correcting FIR fluxes, and show that the data are best fit
by a quiescent spiral template (M51) rather than a warm starburst (M82) or
ULIRG (Arp220), implying a predominance of cold dust in massive galaxies at
high redshift. In contrast we measure total infrared luminosities that are
consistent with high star-formation rates. We observe that the FRC index (q)
does not evolve significantly over z=0-2 when computed from K-corrected 24 or
160-mum photometry, but that using 70-mum fluxes leads to an apparent decline
in q beyond z~1. This suggests some change in the SED at high redshift, either
a steepening of the spectrum at rest-frame ~25-35mum or a deficiency at ~70mum
leading to a drop in the total infrared/radio ratios. We compare our results to
other work in the literature and find synergies with recent findings on the
high-redshift FRC, high specific star-formation rates of massive galaxies and
the cold dust temperatures in these galaxies.
