Footprints in the Wind: Probing X-ray Outflows in NGC 7469 using Near-Infrared Emission Lines

TL;DR

This study addresses the challenge of spatially resolving X-ray AGN winds by leveraging JWST infrared footprint lines that trace the same high-ionization gas. By integrating JWST MIRI/NIRSpec data with archival XMM-Newton RGS and Chandra observations, the authors identify three gas phases—footprint (X-ray), coronal, and nebular—and constrain their ionization properties with Cloudy photoionization modeling. The analysis yields spatially resolved mass outflow rates and energetics, showing the footprint/X-ray component dominates the kinetic energy budget while the overall feedback efficiency remains below the theoretical threshold, indicating weak coupling to the host galaxy. This work demonstrates the utility of IR footprint lines as proxies for soft X-ray gas and establishes a self-consistent, multi-phase view of AGN feedback in NGC 7469, with implications for interpreting X-ray winds in other systems and guiding future XRISM studies.

Abstract

AGN winds play an important role in the co-evolution of supermassive black holes and their host galaxies, yet their driving mechanisms and impact on star formation remain subjects of active investigation. Critically, the lack of X-ray Integral Field Units currently limits our ability to acquire spatially resolved velocity information in the X-ray regime. However, instead, this can be achieved using the James Webb Space Telescope. As part of an ongoing investigation of the nuclear feedback processes in the nearby luminous AGN NGC 7469, we present an analysis of the kinematics of the X-ray emitting outflows using near-infrared footprint lines such as [Mg VIII] 3.03 um. These high-ionization emission lines are associated with the same gas analyzed in the X-ray, and thus can be used to probe the footprint of the X-ray wind's velocity structure and ionization state. Thanks to the wide wavelength range available with JWST we also use nebular (e.g. [S IV] 10.51 um) and coronal (e.g. [Ne V] 14.32 um) emission lines to offer a comprehensive multi-phase view of the outflows. We present mass and kinetic energy outflow rates, and find that while the feedback processes in NGC 7469 are not efficient by theoretical benchmarks, the most massive and energetic component is the high ionization X-ray gas.

Figures (10)

• Figure 1: Multi-component spectral fit for the [Mg vii] $\lambda$5.50 $\upmu$m and adjacent H$_2$S(7) emission lines over the full spatial extent of the observed emission. As described in the text, each line in the data (gray) is modeled using two Gaussian components with systemic in red and the outflow component in blue. We also include a vertical gray line at systemic velocity.
• Figure 2: Cloudy predicted ionic abundances for the ions corresponding to all significantly detected emission lines in the X-ray, NIR and MIR in NGC 7469. The solid lines correspond to those found in the X-ray spectrum, while the dash-dotted and dashed lines correspond to those found in NIRSpec and MIRI, respectively. We separate the coronal and footprint lines (top panel) from the nebular and X-ray lines (bottom panel), and add bands emphasizing the range in ionization parameter where the different phases peak.
• Figure 3: The relative luminosity of modeled values (L$_{mod}$/L$_{obs}$) is shown in brown circles. The closer the point is to unity (dashed black line), the better the modeled value agrees with the observed one. Only the observed IR luminosities and their uncertainties were used to determine the best model parameters, and the uncertainties are shown in green. The measured X-ray luminosity uncertainties are shown in pink.
• Figure 4: Comparing the morphology of the X-ray emission lines and the corresponding footprint lines. We find general agreement between them, with the caveats outlined in the text. The contour levels from outermost to innermost for N vi (f), O vii (f), and C vi Ly$\alpha$ are as follows: [0.15, 0.3, 0.6, 3], [0.35, 0.6, 1.2, 3, 5] and [0.22, 0.35, 0.6, 1.2] respectively and correspond to regions of equal count numbers. The Chandra images were PSF subtracted before creating the contours, as explained in Section \ref{['sec:chandra']}, and the PSF of the IR lines are shown as a circle in the lower right of each map.
• Figure 5: We show a continuum-subtracted map of the [Ar ii] $\lambda$6.99 $\upmu$m line, a star-formation indicator in MIRI/ch1 to demonstrate the position of our regions with respect to the star-forming ring. The map was created using QFitsViewOtt2012. We over-plot the average distance from the center for each circular region of interest as well as the way the circles were further split into six directions: E, NE, NW, W, SW, and SE. The actual spaxels making up each region are shown in the lower left inlay. The white dashed region is the redshifted outflow region detailed in Appendix \ref{['app: redshifted outflow']}.