Kinematic detection of dusty outflows from AGN: PAH kinematics of type 2 quasars with JWST/MIRI spectroscopy

Abstract

Active galactic nuclei (AGN) are thought to have dusty outflows; however, unlike the gas phase, measuring the kinematics of dust is challenging. We present the detection and analysis of the kinematics of dust in five type 2 quasars (QSO2s) at $z\sim0.1$ from the Quasar Feedback (QSOFEED) sample observed with JWST/MIRI spectroscopy. We use Principal Component Analysis (PCA) tomography to produce velocity maps of Polycyclic Aromatic Hydrocarbon (PAH) features, which are the smallest carbonaceous dust particles. We are then able to compare velocity maps of the PAHs with emission lines of ionised and molecular gas. We are able to produce velocity maps of the 11.3 $μ$m PAH feature, which traces large and neutral PAHs, for three out of the five objects where all three show the presence of an outflow in the PAH kinematics. This becomes particularly clear after subtracting disk kinematics, where the H$_2$ rotational transitions also show residuals consistent with an outflow. Compared to previous work with Seyfert galaxies, this work suggests that dusty outflows are more common at higher Eddington ratios, $λ_{\rm Edd}\gtrsim0.1$, in agreement with previous suggestions, although the sample size is small. We are unable to produce velocity maps for the 6.2 $μ$m PAH, which traces ionised PAHs, potentially due to differences in the intrinsic profile and/or suppression of the feature in AGN, which was seen previously in Seyfert galaxies. This reflects studies of PAH band ratios where AGN outflows have more neutral PAHs. This work demonstrates that dusty outflows may be common, particularly at high Eddington ratios, and therefore play a key role in the evolution and life cycle of AGN.