Theoretical models of quasar feedback involve radiatively-driven nuclear
winds, which propagate into the surrounding interstellar gas (causing shock
heating and plowed shells) and resulting in a galaxy-wide wind over the
life time of the quasar. There are, however, few observational probes of
this particular feedback phenomenon. One relatively unexplored route is to
search for the shocked gas in the radio. Though only about 15% of quasars
are traditionally “radio-loud”, meaning they launch radio jets that can be
observed on scales of hundreds of kiloparsecs, we can identify populations
of traditionally ‘radio-quiet’ quasars that produce more radio emission
than can be easily explained by just star formation. Indeed, the radio
luminosity of powerful radio-quiet and radio- intermediate quasars is
correlated with the velocity dispersion of ionized gas (measured via the
strong [OIII]λ5007Å emission line), suggesting an intimate connection
between radio emission and gas outflows. Recent upgrades to the Karl G.
Jansky Very Large Array (VLA) allow for radio observations with
unprecedented sensitivity and resolution, opening the radio regime as an
additional avenue for studying multi-phase quasar winds and the interaction
between quasars and their host galaxies. I will present our recent studies
on the radio emission from radio-quiet quasars at both z~0.5 and z~2.5
where we use a combination of radio luminosity, spectral index and
morphology in an attempt to disentangle jet- and wind-driven radio
emission. In addition, I will present preliminary results from a recent
radio survey of z~0.5 quasars with multi-component [OIII] 5007 emission
which suggests either the presence of bi-conical outflows or dual
supermassive black holes and show how radio data allows us to disentangle
these scenarios. Such studies are of increasing importance as we plan for
the Next Generation Very Large Array (ngVLA) whose unprecedented resolution
and sensitivity will allow us to better disentangle various competing
quasar feedback scenarios.
Wishing you clear skies,
