What is the origin of the soft excess in AGN?

Abstract

We investigate the nature of the soft excess below 1 keV observed in AGN. We use the XMM-Newton data of the low redshift, optically bright quasar, PG 1211+143, and we compare it with the Narrow Line Seyfert 1 galaxy, 1H 0707-495, which has one of the strongest soft excesses seen. We test various ideas for the origin of the soft X-ray excess, including a separate spectral component (for example, low temperature Comptonized emission), a reflection-dominated model, or a complex absorption model. All three can give good fits to the data, and chi^2 fitting criteria are not sufficient to discriminate among them. Instead, we favour the complex absorption model on the grounds that it requires less extreme parameters. In particular the geometry appears to be more physically plausible as the reflected component in the smeared absorption model is no longer dominant, and relativistic distortions, while still clearly present, are not tremendously larger than expected for a disc around a Schwarzchild black hole.

MNRAS accepted

References in corpus (6)

• X-ray Properties of Black-Hole Binaries
• XMM-Newton study of the complex and variable spectrum of NGC 4051
• Investigating the nature of narrow-line Seyfert 1 galaxies with high-energy spectral complexity
• Energy-dependent variability and the origin of the soft X-ray excess in AGN
• Lens-Aided Multi-Angle Spectroscopy (LAMAS) Reveals Small-Scale Outflow Structure in Quasars
• Failed disk winds; a physical origin for the soft X-ray excess?

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