Tracking X-ray outflows with optical/infrared footprint lines. Issue 1 (27th January 2022)

• Record Type: Journal Article
• Authors: Trindade Falcão, Anna; Kraemer, S B; Crenshaw, D M; Melendez, M; Revalski, M; Fischer, T C; Schmitt, H R; Turner, T J
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 511:Issue 1(2022)
• Page Start: 1420
• Page End: 1430
• Publication Date: 2022-01-27
• Subjects: galaxies: active -- galaxies: kinematics and dynamics -- galaxies: Seyfert -- X-rays: galaxies; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stac173
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We use cloudy photoionization models to predict the flux profiles for optical/infrared (IR) emission lines that trace the footprint of X-ray gas, such as [Fe x ] 6375 Å and [Si x ] 1.43 $\mu\mathrm{m}$ . These are subset of coronal lines, from ions with ionization potential greater than or equal to that of O vii, i.e. 138 eV. The footprint lines are formed in gas over the same range in ionization state as the H- and He-like of O and Ne ions, which are also the source of X-ray emission lines. The footprint lines can be detected with optical and IR telescopes, such as the Hubble Space Telescope /STIS and James Webb Space Telescope /NIRSpec, and can potentially be used to measure the kinematics of the extended X-ray emission gas. As a test case, we use the footprints to quantify the properties of the X-ray outflow in the type 1 Seyfert galaxy NGC 4151. To confirm the accuracy of our method, we compare our model predictions to the measured flux from archival STIS spectra and previous ground-based studies, and the results are in good agreement. We also use our X-ray footprint method to predict the mass profile for the X-ray emission-line gas in NGC 4151 and derive a total spatially integrated X-ray mass of $7.8(\pm 2.1) \times 10^{5}\, {\rm M}_{\odot }$, in comparison to $5.4(\pm 1.1) \times 10^{5}\, {\rm M}_{\odot }$ measured from a Chandra X-ray analysis. Our results indicate that high-ionization footprint emission lines in the optical and near-IR can be used to accurately trace the kinematics and physical conditions of active galactic nucleus-ionized, X-ray emission-line gas.