A two-zone model for the broad iron line emission in MCG–6-30-15期刊界 All Journals 搜尽天下杂志传播学术成果专业期刊搜索期刊信息化学术搜索

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A two-zone model for the broad iron line emission in MCG–6-30-15

Authors:	R Misra

Institution:	Department of Physics &Astronomy, Northwestern University, Evanston, IL 60208, USA

Abstract:	We reanalyse the ASCA and BeppoSAX data of MCG–6-30-15, using a double-zone model for the iron line profile. In this model, the X-ray source is located around ≈10 Schwarzschild radii and the regions interior and exterior to the X-ray source produce the line emission. We find that this model fits the data with a similar reduced χ ² to the standard single-zone model. Thus we show that the presence of a broad iron line feature does not necessarily require that the X-ray source be located close to the last stable orbit or in the disc rotation axis. Within the framework of this model, the best-fitting inclination angle of the source for the intermediate-intensity ASCA data set is compatible with that determined by earlier modelling of optical lines. The observed variability of the line profile with intensity can be explained as variations of the X-ray source size. That several active galactic nuclei with broad lines have the peak centroid near 6.4 keV can be explained under certain conditions. We also show that the simultaneous broad-band observations of this source by BeppoSAX rule out the Comptonization model which was an alternative to the standard inner-disc one. We thereby strengthen the case that line broadening occurs as a result of the strong gravitational influence of a black hole.

Keywords:	accretion accretion discs black hole physics line: profiles galaxies: individual: MCG–6-30-15 galaxies: Seyfert

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