Probing the Wind Component of Radio Emission in Luminous High-redshift Quasars

Abstract

We discuss a probe of the contribution of wind-related shocks to the radio emission in otherwise radio-quiet quasars. Given (1) the nonlinear correlation between UV and X-ray luminosity in quasars, (2) that such a 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 ≃ 1.65 color-selected quasars that span the range of expected accretion disk wind properties as traced by broad C iv emission. 3 GHz observations with the Very Large Array to an rms of ≈10 μJy beam−1 probe to star formation rates of ∼400 M ⊙ yr−1, leading to 22 detections. Supplementing these pointed observations are survey data of 388 sources from the LOFAR Two-meter 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 nonlinear function of C iv 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 Eddington 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.

A fresh look at AGN spectral energy distribution fitting with the XMM-SERVS AGN sample

“…These emission line property values are analogous to the emission line range shown in the top of Fig. 3 in Richards et al (2021). Negative values of the emission line type correspond to highly blueshifted, weak emission lines similar to objects in the bottom right of Richards et al (2021) Fig.…”

“…3 in Richards et al (2021). Negative values of the emission line type correspond to highly blueshifted, weak emission lines similar to objects in the bottom right of Richards et al (2021) Fig. 3, whereas positive values of the emission line property correspond to stronger, more symmetrical emission lines, similar to objects in the top left of that figure.…”

Connecting radio emission to AGN wind properties with Broad Absorption Line Quasars

“…Kratzer et al (2015) also finds that the radio loudness fraction of quasars decreases as the presence of strong radiation line-driven winds increases. Most recently Richards et al (2021) finds that the radio detection fraction is a non-linear function of C emission properties. They argue that their sample of radio-quiet quasars may require multiple multiple radio emission mechanisms to fully explain their radio observations with the VLA and LOFAR.…”

Connection between Emission and Absorption Outflows through the Study of Quasars with Extremely-High Velocity Outflows

“…Each quasar can then be projected onto the best-fit line and a C iv distance value is assigned. This metric was first introduced by Rivera et al (2020) to better explore the variability of the SDSS Reverberation Mapping quasars (Shen et al 2015) and by Richards et al (2021) to investigate radio trends in C iv space. Rivera et al (2022) suggest that C iv distance can be used as a proxy for the Eddington ratio and so the Heii EW (thus the SED hardness) is anti-correlated with the Eddington ratio.…”