Comment on "The dust sublimation radius as an outer envelope to the bulk of the narrow Fe K$\alpha$ line emission in Type 1 AGN"

TL;DR

This paper compares recent findings on the location of the narrow Fe Kα emission region in AGNs with previous work, highlighting their consistency and discussing differences in methodology and scope.

Contribution

It provides a brief comparison of two studies on Fe Kα emission regions, clarifying their similarities and differences in approach and findings.

Findings

Gandhi et al.'s results support Minezaki & Matsushita's earlier conclusions.

Both studies find the Fe Kα emission region is close to the dust sublimation radius.

The comparison clarifies methodological differences between individual measurements and scaling relations.

Abstract

Recently, Gandhi, H\"onig, and Kishimoto submitted a manuscript to the arXiv e-print service on the location of the emitting region of the narrow FeK$\alpha $ line that appears in the X-ray spectra of active galactic nuclei (AGNs) compared with the inner radius of the dust torus (arXiv:1502.02661). Prior to their manuscript, a similar discussion had already been presented in a section of Minezaki & Matsushita (2015), which had been accepted for publication in the Astrophysical Journal. Because Gandhi et al. made no reference to Minezaki & Matsushita (2015) apart from improperly citing it merely as an application of the dust reverberation of AGNs, we present a brief comparison of both papers. Gandhi et al. compared the location of the FeK$\alpha$ emitting region with the individually measured radius of the dust torus for type 1 AGNs, whereas Minezaki & Matsushita (2015) examined it based on the scaling relation of the dust reverberation radius for both type 1 and type 2 AGNs. Nevertheless, Gandhi et al's main result is basically consistent with and supports the results of Minezaki & Matsushita (2015).