XRISM/Resolve Spectroscopy of the Central Engine in the Seyfert-1 AGN Mrk 279

TL;DR

This study utilizes high-resolution XRISM spectroscopy to analyze the central engine of Seyfert-1 galaxy Mrk 279, revealing complex emission line components, potential ultra-fast outflows, and insights into the structure of the AGN's inner regions.

Contribution

First XRISM/Resolve spectrum of Mrk 279 providing detailed velocity components and potential ultra-fast outflows, advancing understanding of AGN inner structures.

Findings

Velocity components linked to torus, BLR, and accretion disk

Detection of highly ionized Fe XXVI emission line

Possible ultra-fast outflows with velocities around 0.2-0.3c

Abstract

High-resolution X-ray spectroscopy with XRISM gives an unprecedented view of the ``central engine'' in active galactic nuclei, providing unique insights into black hole accretion and feedback. We present an analysis of the first XRISM/Resolve spectrum of the Seyfert-1 galaxy Mrk 279, known for its complex line profiles and variability. The data reveal velocity components within the Fe K$_{\alpha}$ emission line that can be associated with the inner face of the molecular torus ($r \geq 10^{4}~GM/c^{2})$, the broad line region (BLR; $r = 1650^{+5780}_{-1480}~GM/c^{2}$), and the inner accretion disk ($r = 81^{+280}_{-75}~GM/c^{2}$). We find evidence of low-velocity, highly ionized gas that contributes an H-like Fe XXVI emission line at 6.97 keV, confirming suggestions from prior low-resolution spectra. The data do not show slow winds in absorption, but two pairs of lines - consistent with He-like and H-like Fe shifted by $v\simeq 0.22c$ and $v\simeq 0.33c$ - improve the fit, and could represent an ultra-fast outflow (UFO). Their addition to the model only reduces the Akaike Information Criterion by 3.6 and 3.5, respectively, signaling modest support. Additional observations are needed to definitively test for the presence of fast X-ray winds in Mrk 279. We discuss these results in the context of the geometry of the central engine in AGN, emerging trends in XRISM studies of AGN, and the nature of the potential UFOs.