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Astronomický ústav 
Akademie věd České republiky
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Pravidelný seminář 5. 4. 2004


Pozvánka na pravidelný seminář AsÚ AV ČR

který se koná v pondělí dne
5. dubna 2004

v nové seminární místnosti AsÚ v Ondřejově
 

PROGRAM:

13:00 odborná část
14:00 přestávka/káva
14:20 informace z vedení ústavu

V odborné části vyslechneme informace ze stelárního oddělení:

1. Novinky z oddělení (Jiří Kubát)
2. Přednáška 

Michal Dovčiak

General relativistic models of spectra of X-ray sources with strong gravity

It is possible to probe the innermost regions of an accretion disc near a black hole, either in the active galactic nuclei or in galactic black hole candidates, by recent X-ray missions (Chandra, XMM-Newton). The need arises for fast data fitting procedures that take into account all general relativistic effects and determine in this way parameters of the black hole -- accretion disc system. We will report on a new set of such routines we deviced that can be used within the X-ray spectral fitting package XSPEC.

We first summarize various effects of general relativity that influence the emission from close vicinity of the black hole. One of the manifestations of the interaction of the emission from the accretion disc with the gravitation of the black hole is a broad fluorescent iron line emitted from the disc after primary X-ray illumination. Furthermore, narrow spectral features in the 5--6 keV range were recently discovered in the X-ray spectra of a few active galactic nuclei, and these can as well be interpreted as line emission from localized spots in strong gravity regime. We take these examples as an application of our routines and present some of the results.

New missions are planned (Astro-E2, Constellation-X and Xeus) that will reach better resolution, both in energy and timing, and acquire more information including polarimetry. Therefore, exciting investigations of close vicinity of the black holes seems to be on a good track.

For further details, see recent papers at http://esoads.eso.org/cgi-bin/nph-abs_connect?db_key=AST&db_key=PRE&author=dovciak
 
 
 
Srdečně zve
 
Vladimír Karas 
vedoucí semináře