Kinematic detection of dusty outflows from active galactic nuclei: Polycyclic aromatic hydrocarbon kinematics of type 2 quasars with JWST/MIRI spectroscopy

Fergus R. Donnan, Cristina Ramos Almeida, Omaira González Martín, Karin Sandstrom, Anelise Audibert, Marina Bianchin, Miguel Pereira-Santaella, Ismael García-Bernete

First listed 2026-06-29 | Last updated 2026-07-03

Abstract

Active galactic nuclei (AGN) are thought to have dusty outflows, but unlike in the gas phase, it is challenging to measure the kinematics of dust. We present the detection and analysis of the kinematics of dust in five type 2 quasars at $z\sim0.1$ from the Quasar Feedback (QSOFEED) sample observed with JWST/MIRI spectroscopy. We used principal component analysis tomography to produce velocity maps of polycyclic aromatic hydrocarbon (PAH) features, which are the smallest carbonaceous dust particles. We were then able to compare velocity maps of the PAHs with emission lines of ionised and molecular gas. We produced 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 an outflow in the PAH kinematics. This becomes particularly clear after we subtracted 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 were 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 it therefore plays a key role in the evolution and life cycle of AGN.

Short digest

This paper uses JWST/MIRI MRS observations of five z~0.1 QSOFEED type 2 quasars and PCA tomography of PAH features to directly probe dust kinematics. The main result is that the 11.3 μm PAH feature yields velocity maps in three systems, and all three show PAH outflows, most clearly after subtracting rotating-disk kinematics, with H2 rotational lines leaving consistent residual outflow signatures. By comparison with lower-Eddington-ratio Seyferts, the authors argue that dusty outflows are likely more common when λ_Edd ≳ 0.1, in line with these luminous QSO2s occupying blowout or polar-wind territory. They do not recover usable 6.2 μm PAH velocity maps, which is consistent with ionised or smaller PAHs being profile-variable or suppressed in AGN, so the strongest kinematic evidence here comes from the more neutral 11.3 μm carriers.

Key figures to inspect

• Figure 2. This PCA decomposition for J1509 is the clearest methods figure because it shows exactly which eigenspectrum carries the PAH velocity information and which component is dominated by PSF-subtraction artifacts. It helps the reader see why PCA tomography is necessary for broad PAH bands whose intrinsic profiles make conventional spaxel-by-spaxel fitting difficult.
• Figure 3. These sample-wide velocity maps are the core overview figure because they place the PAH, ionised-gas, and molecular-gas kinematics side by side for all five quasars on a common velocity scale. This is where the reader can immediately see that 11.3 μm PAH kinematics are only recovered in three objects and compare those patterns to the host-galaxy disk major axes.
• Figure 6. The disk-subtracted velocity maps for J1509 provide one of the cleanest demonstrations that the PAH signal is tracing an outflow rather than simple disk rotation. The added CO(2-1) contours and the separate PAH and H2 outflow position angles make this a strong multi-phase evidence figure for the paper’s central claim.
• Figure 9. This comparison of column density versus Eddington ratio is the main synthesis figure linking the new QSO2 detections to the earlier Seyfert sample. It matters because it visually supports the paper’s broader interpretation that dusty PAH outflows become more common in the blowout or IR polar-outflow regime at higher λ_Edd.
• Figure 10. These velocity profiles along the outflow axis for J1509, J1430, and J1100 are the most direct kinematic comparison between the 11.3 μm PAH feature and the H2 lines after disk subtraction. They show how the dusty and molecular components track each other spatially and kinematically across the three detections, strengthening the case for a genuine outflowing dusty phase.