Probing the Wind Component of Radio Emission in Luminous High-Redshift
  Quasars
  We discuss a probe of the contribution of wind-related shocks to the radio
emission in otherwise radio-quiet quasars. Given 1) the non-linear correlation
between UV and X-ray luminosity in quasars, 2) that such correlation leads to
higher likelihood of radiation-line-driven winds in more luminous quasars, and
3) that luminous quasars are more abundant at high redshift, deep radio
observations of high-redshift quasars are needed to probe potential
contributions from accretion disk winds. We target a sample of 50 $z\simeq
1.65$ color-selected quasars that span the range of expected accretion disk
wind properties as traced by broad CIV emission. 3-GHz observations with the
Very Large Array to an rms of $\approx10\mu$Jy beam$^{-1}$ probe to star
formation rates of $\approx400\,M_{\rm Sun}\,{\rm yr}^{-1}$, leading to 22
detections. Supplementing these pointed observations are survey data of 388
sources from the LOFAR Two-metre Sky Survey Data Release 1 that reach
comparable depth (for a typical radio spectral index), where 123 sources are
detected. These combined observations reveal a radio detection fraction that is
a non-linear function of \civ\ emission-line properties and suggest that the
data may require multiple origins of radio emission in radio-quiet quasars. We
find evidence for radio emission from weak jets or coronae in radio-quiet
quasars with low Eddingtion ratios, with either (or both) star formation and
accretion disk winds playing an important role in optically luminous quasars
and correlated with increasing Eddington ratio. Additional pointed radio
observations are needed to fully establish the nature of radio emission in
radio-quiet quasars.
