Exploring the quasar disc-wind-jet connection with LoTSS and SDSS

Abstract

We investigate the relationship between disc winds, radio jets, accretion rates and black hole masses of a sample of $\sim$100k quasars at z $\approx$ 2. Combining spectra from the 17th data release of the Sloan Digital Sky Survey (SDSS) with radio fluxes from the 2nd data release of the Low Frequency ARray (LOFAR) Two-Meter Sky Survey (LoTSS), we statistically characterise a radio loud and radio quiet population using a two-component Gaussian Mixture model, and perform population matching in black hole mass and Eddington fraction. We determine how the fraction of radio loud sources changes across this parameter space, finding that jets are most efficiently produced in quasars with either a very massive central black hole ($M_{\textrm{BH}} > 10^9 \textrm{M}_{\odot}$) or one that is rapidly accreting ($λ_{\textrm{Edd}}>0.3$). We also show that there are differences in the blueshift of the CIV $λ$1549Å line and the equivalent width of the HeII $λ$1640Å line in radio loud and radio quiet quasars that persist even after accounting for differences in the mass and accretion rate of the central black hole. Generally, we find an anti-correlation between the inferred presence of disc winds and jets, which we suggest is mediated by differences in the quasars' spectral energy distributions. The latter result is shown through the close coupling between tracers of wind kinematics and the ionising flux -- which holds for both radio loud and radio quiet sources, despite differences between their emission line properties -- and is hinted at by a different Baldwin effect in the two populations.

Figures (19)

• Figure 1: Sky coverage of the surveys used in this work. The Sloan Digital Sky Survey DR17 subset constructed by temple2023 (red), LOFAR Two-Meter Sky Survey DR2 optical identifications catalogue (blue), and the resulting overlapping sample (yellow).
• Figure 2: Distribution of quasars in $L_{3000}$ and 144 MHz radio luminosity. The colour of the points corresponds to the cluster to which the source has been assigned by the two-component GMM, with Cluster 1 (red) defining radio-loud and Cluster 2 (blue) defining radio-quiet sources. The shading of the points indicates the probability of the source being correctly assigned to its cluster, with darker colours showing less certainty. The solid black line shows the classical radio loudness cut at log$_{10}(R)>2.5$, and the dashed line indicates the $10^{26}$ W Hz$^{-1}$ radio luminosity cut. The stars show sources with multiple ($>1$) associated components in the LoTSS DR2 value-added catalogue.
• Figure 3: Distributions of radio loud (red points/contours) and radio quiet (blue points/contours) quasars in $L_{3000}$ and $\textrm{FWHM}_{\textrm{$\textrm{Mg}\,\textsc{ii}$}}$ space, for the entire sample (left) and then after NearestNeighbour matching in this space (right). The RL and RQ populations are as defined by the GMM. The matching procedure has removed any differences in these distributions.
• Figure 4: The $\textrm{C}\,\textsc{iv}$ blueshift and $\textrm{EW}_{\textrm{$\textrm{C}\,\textsc{iv}$}}$ distributions for radio loud (red points/contours) and radio quiet (blue points/contours) quasars, as defined by the GMM. Similarly to Fig. \ref{['fig:pre-match']}, the left plot is for the entire sample, and the right shows the distribution of sources after they are matched in $L_{3000}$ and $\textrm{FWHM}_{\textrm{$\textrm{Mg}\,\textsc{ii}$}}$. There are clearly differences in both distributions, even after effectively accounting for black hole mass and Eddington fraction.
• Figure 5: Distribution of radio loud (red points/contours) and radio quiet (blue points/contours) quasars in $L_{3000}$ and the EW of ultraviolet emission lines, $\textrm{C}\,\textsc{iv}$ (left) and $\textrm{He}\,\textsc{ii}$ (right), for populations matched in $L_{3000}$ and FWHM$_{\textrm{$\textrm{Mg}\,\textsc{ii}$}}$. The RL and RQ populations here are defined by the GMM.