Relativistic Fe Kα line study in Seyfert 1 galaxies observed with Suzaku

• Published in: Monthly notices of the Royal Astronomical Society Vol. 458; no. 4; pp. 4198 - 4209
• Main Authors: Mantovani, G., Nandra, K., Ponti, G.
• Format: Journal Article
• Language: English
• Published: Oxford University Press 01-06-2016
• Subjects: Continuums; Emission analysis; Galaxies; Reflection; Seyfert galaxies; Spectral lines; Symbols; XMM (spacecraft); galaxies: Seyfert; black hole physics; galaxies: active; accretion, accretion discs; X-rays: galaxies
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stw596

We present an analysis of a sample of Seyfert 1 galaxies observed with Suzaku. The aim of this work is to examine critically the evidence for a relativistic Fe Kα line in the X-ray spectra of these active galactic nuclei. The sample was compiled from those sources in which a relativistic component was missing in at least one XMM–Newton observation. We analysed the Suzaku spectra of these objects in order to have more constraints on the high-energy emission, including the Compton reflection hump. The results show that the relativistic Fe Kα line is detected (at >95 per cent confidence) in all sources observed with high-signal-to-noise ratio (e.g. where the counts in the 5–7 keV energy band are ≳4 × 104). This is in agreement with the idea that relativistic lines are a ubiquitous feature in the spectra of Seyfert galaxies, but are often difficult to detect without very high-quality data. We also investigate the relation between the Fe Kα line and the reflection continuum at high energies. For most of the sample, the strength of the reflection component is consistent with that of the line. There are exceptions in both senses, however i.e. where the reflection continuum is strong but with weak line emission, and vice versa. These observations present a challenge for standard reflection models.