Revealing Intermediate Disk Radii in NGC 4151 with Chandra
Abstract
Chandra HETG spectra of the nearby Seyfert AGN NGC 4151 reveal asymmetry in the profile of the narrow, neutral Fe K emission line. Numerous fits with both simple line models, and physical models including weak relativistic effects and scattering, strongly suggest that the line originates at radii less than R ~ 500-1000 GM/c^2. There is evidence that the line is broader when the flux is higher, potentially originating just R ~ 50-100 GM/c^2 from the black hole in high flux states. This differs from the relationship expected based on photoionization, although the latter is strongly confirmed in optical broad line variability studies. We discuss our findings in the context of geometric structures in the inner and intermediate disk and the nature and origin of the broad line region in Seyferts, and note that narrow Fe K line reverberation may be used to measure black hole masses using XRISM and Athena.
- Publication:
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AAS/High Energy Astrophysics Division
- Pub Date:
- March 2019
- Bibcode:
- 2019HEAD...1710643M