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ESAC Grid Workshop, Madrid : Espagne (2006)
Magnetic flares in Active Galactic Nuclei: Modeling the iron Kalpha-line
R.W. Goosmann1, B. Czerny, M. Mouchet1, 2, V. Karas, M. Dovciak, G. Ponti, A. Rozanska, A.-M. Dumont1

The X-ray spectra of Active Galactic Nuclei (AGN) are complex and vary rapidly in time as seen in recent observations. Magnetic flares above the accretion disk can account for the extreme variability of AGN. They also explain the observed iron Kalpha fluorescence lines. We present radiative transfer modeling of the X-ray reflection due to emission from magnetic flares close to the marginally stable orbit. The hard X-ray primary radiation coming from the flare source illuminates the accretion disk. A Compton reflection/reprocessed component coming from the disk surface is computed for different emission directions. We assume that the density structure remains adjusted to the hydrostatic equilibrium without external illumination because the flare duration is only a quarter-orbit. The model takes into account the variations of the incident radiation across the hot spot underneath the flare source. The integrated spectrum seen by a distant observer is computed for flares at different orbital phases close to the marginally stable orbit of a Schwarzschild black hole and of a maximally rotating Kerr black hole. The calculations include relativistic and Doppler corrections of the spectra using a ray tracing technique. We explore the practical possibilities to map out the azimuthal irradiation pattern of the inner accretion disks and conclude that the next generation of X-ray satellites should reveal this structure from iron Kalpha line profiles and X-ray lightcurves.
1 :  LUTH - Laboratoire Univers et Théories
2 :  APC - UMR 7164 - AstroParticule et Cosmologie
APC - Cosmologie et gravitation
Planète et Univers/Astrophysique

Physique/Astrophysique/Cosmologie et astrophysique extra-galactique

Planète et Univers/Astrophysique/Cosmologie et astrophysique extra-galactique
accretion – accretion disks – galaxies: active – radiative transfer – relativity – X-rays: galaxies
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