Jiri Svoboda
email:
phone: +420 267 103 119
Jiri Svoboda is a PhD student with Vladimir Karas. He investigates the innermost parts of accretion discs of active galactic nucleii and black hole binaries by examining relativistically broadened iron lines observed by X-ray satellites.
Recent observations by X-ray satellites (XMM-Newton, Chandra) reveal the presence of relativistically broadened iron lines in some spectra of active galaxies and compact binaries. They are part of the reflection component originating in the innermost parts of accretion discs. Such broadening of the lines is likely caused by the presence of strong gravitational fields and rapid rotational velocities of the radiating matter. The investigation of this component of the spectrum provides a unique way to inspect the region within several gravitational radii from the centre. The geometry of the system can be explored by fitting the observed broadened line using a suitable model, which includes all relativistic effects, i.e. light bending, time delays and lensing. The KY code was developed for this purpose. Our aim is to expand the present spectral analysis of observed broad iron lines by applying the KY code, which represents one of the most detailed ray-tracing models available to date and allows to constrain fundamental physical parameters of the system, including the black hole spin.