2001/02/13 by P. T. Życki, P. T. Zycki, A. Rozanska +1 · 1 citation
Physics and Astronomy · #Accretion (finance) #Accretion disc #Active galactic nucleus #Amplitude #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Cosmic Phenomena #Emission spectrum #Galaxies: Formation, Evolution, Phenomena #Galaxy #Geometry #Instability #Ion #Ionization #Line (geometry) #Nuclear physics #Observable #Optics #Physics #Plasma #Spectral line #X-ray #astro-ph
paper · pdf · doi:10.1046/j.1365-8711.2001.04398.x
published as Mon.Not.Roy.Astron.Soc. 325 (2001) 197 · 12 pages. MNRAS, accepted
arxiv created 2001/02/13 · openalex publication_date 2001/07/11 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
A number of recent results from X-ray observations of active galactic nuclei involving the Fe Kα line (reduction of line variability compared with the X-ray continuum variability, the X-ray ‘Baldwin effect’) were attributed to the presence of a hot, ionized skin of an accretion disc, suppressing emission of the line. The ionized skin appears as a result of the thermal instability of X-ray irradiated plasma. We test this hypothesis by computing the Thomson thickness of the hot skin on top of the αPtot Shakura–Sunyaev disc, by simultaneously solving the vertical structure of both the hot skin and the disc. We then compute a number of relations between observable quantities, e.g. the hard X-ray flux, amplitude of the observed reprocessed component, relativistic smearing of the Kα line and rms variability of the hard X-rays. These relations can be compared with present and future observations. We point out that this mechanism is unlikely to explain the behaviour of the X-ray source in MCG–6-30-15, where there are a number of arguments against the existence of a thick hot skin, but it can work for some other Seyfert 1 galaxies.