A tale of two feedbacks: star-formation in the host galaxies of
  radio-AGN
  Several lines of argument support the existence of a link between activity at
the nuclei of galaxies, in the form of an accreting supermassive black hole,
and star-formation activity in these galaxies. The exact nature of this link is
still under debate. Radio jets have long been argued to be an ideal mechanism
that allows AGN to interact with their host galaxy and regulate star-formation.
In this context, we are using a sample of radio sources in the North Ecliptic
Pole (NEP) field to study the nature of the putative link between AGN activity
and star-formation. This is done by means of spectral energy distribution (SED)
fitting. We use the excellent spectral coverage of the AKARI infrared space
telescope together with the rich ancillary data available in the NEP to build
SEDs extending from UV to far-IR wavelengths. Through SED fitting we constrain
both the AGN and host galaxy components. We find a significant AGN component in
our sample of relatively faint radio-sources ($<$mJy), that increases in power
with increasing radio-luminosity. At the highest radio-luminosities, the
presence of powerful jets dominates the radio emission of these sources. A
positive correlation is found between the luminosity of the AGN component and
that of star-formation in the host galaxy, independent of the radio luminosity.
By contrast, for a given redshift and AGN luminosity, we find that increasing
radio-luminosity leads to a decrease in the specific star-formation rate. The
most radio-loud AGN are found to lie on the main sequence of star-formation for
their respective redshifts. For the first time, such a two-sided feedback
process is seen in the same sample. We conclude that radio jets do suppress
star-formation in their host galaxies but appear not to totally quench it. Our
results therefore support the maintenance nature of "radio-mode" feedback from
radio-AGN jets.
