The contribution of star-forming galaxies to the cosmic radio background
  Recent measurements of the temperature of the sky in the radio band, combined
with literature data, have convincingly shown the existence of a cosmic radio
background with an amplitude of $\sim 1$ K at 1 GHz and a spectral energy
distribution that is well described by a power law with index $\alpha \simeq
-0.6$. The origin of this signal remains elusive, and it has been speculated
that it could be dominated by the contribution of star-forming galaxies at high
redshift \change{if the far infrared-radio correlation $q(z)$ evolved} in time.
\change{We fit observational data from several different experiments by the
relation $q(z) \simeq q_0 - \beta \log(1+z)$ with $q_0 = 2.783 \pm 0.024$ and
$\beta = 0.705 \pm 0.081$ and estimate the total radio emission of the whole
galaxy population at any given redshift from the cosmic star formation rate
density at that redshift. It is found that} star-forming galaxies can only
account for $\sim$13 percent of the observed intensity of the cosmic radio
background.
