On the emitting region of X-ray fluorescent lines around Compton-thick AGN

Abstract

X-ray fluorescent lines are unique features of the reflection spectrum of the torus when irradiated by the central AGN. Their intrinsic line width can be used to probe the line-emitting region. Previous studies have focused on the Fe Ka line at 6.4 keV, which is the most prominent fluorescent line. These studies, however, are limited by the spectral resolution of currently available instruments, the best of which is $\sim 1860$ km s${}^{-1}$ afforded by the Chandra High-Energy Grating (HEG). The HEG spectral resolution is improved by a factor of 4 at 1.74 keV, where the Si Ka line is located. We measured the FWHM of the Si Ka line for Circinus, Mrk 3, and NGC 1068, which are $570\pm 240$, $730\pm 320$, and $320\pm 280$ km s${}^{-1}$, respectively. They are $3-5$ times smaller than those measured with the Fe Ka line previously. It shows that the intrinsic widths of the Fe Ka line are most likely to be over-estimated. The measured widths of the Si Ka line put the line-emitting region outside the dust sublimation radius in these galaxies. It indicates that for Compton-thick AGN, the X-ray fluorescence material are likely to be the same as the dusty torus emitting in the infrared.

4 pages, 1 fig, to appear on MNRAS

References in corpus (8)

• Revisiting the Unified Model of Active Galactic Nuclei
• Reverberation Measurements of the Inner Radius of the Dust Torus in 17 Seyfert Galaxies
• The 2-79 keV X-ray Spectrum of the Circinus Galaxy with NuSTAR, XMM-Newton and Chandra: a Fully Compton-Thick AGN
• The dust sublimation radius as an outer envelope to the bulk of the narrow Fe Kalpha line emission in Type 1 AGN
• An X-ray spectral model for clumpy tori in active galactic nuclei
• A New Black Hole Mass Estimate for Obscured Active Galactic Nuclei
• X-ray fluorescent lines from the Compton-thick AGN in M51
• The clumpy torus around type II AGN as revealed by X-ray fluorescent lines

Cited by in corpus (4)

• X-ray Constraint on Location of AGN Torus in Circinus Galaxy
• X-ray signatures of the polar dusty gas in AGN
• The intrinsic line width of the Fe Ka line of AGN
• The clumpy torus around type II AGN as revealed by X-ray fluorescent lines