Seminars 2010
28.07.2010 15:00
Thomas Dauser
Dr. Karl Remeis-Sternwarte, Astronomisches Institut, Universität Erlangen-Nürnberg
Broad emission lines for a negatively spinning black hole
Abstract
Thomas Dauser
Broad emission lines for a negatively spinning black hole
We present an extended scheme for the calculation of the profiles of emission lines from accretion discs around rotating black holes. The scheme includes discs with angular momenta which are parallel and antiparallel with respect to the black hole's angular momentum, as both configurations are assumed to be stable (King et al., 2005). We discuss line shapes for such discs and present a code for modelling observational data with this scheme in X-ray data analysis programs. Based on a Green's function approach, an arbitrary radius dependence of the disc emissivity and arbitrary limb darkening laws can be easily taken into account, while the amount of precomputed data is significantly reduced with respect to other available models.
28.04.2010 10:00
Michal Bursa
Astronomical Institute, Academy of Sciences, Prague
Black holes yesterday, today and tomorrow
Abstract
Michal Bursa
Black holes yesterday, today and tomorrow
Summary of the conference "Probing strong gravity near black holes", 15-18 February 2010
19.04.2010 14:00
David Kofron
Faculty of Mathematics and Physics, Charles University in Prague
Theory of relativity in our lives and in the stars
Abstract
David Kofron
Theory of relativity in our lives and in the stars
(Lecture for general public)
At the beginning we touch upon the relation between physics and philosophy - or, rather, just the relation between theory and experiment. A short historical discourse about the crucial changes in the paradigms of physics follows. We mention three most influential figures of physics: Newton, Maxwell and Einstein. Then we analyze what motivated scientists (not only Einstein) to invent theories of special and general relativity. The use of these abstract theories even in our lives! is shown by examples. The second part of the lecture is devoted to astrophysical laboratories of general relativity found in the distant universe, the double pulsar PSR J0737-3039A/B being the exceptional one.
22.03.2010 14:00
Lubos Pick
Faculty of Mathematics and Physics, Charles University in Prague
The Pea and The Sun
Abstract
Lubos Pick
The Pea and The Sun
The talk will be dedicated to the famous (or perhaps rather infamous) 1924 result of S. Banach and A. Tarski which ignited at its time a lot of controversy not only among mathematicians. This topic, whose nature puts it somewhere near the crossroads of the set theory and the measure theory, and which was later on called the Banach-Tarski Paradox, is a beautiful and amusing illustration of certain specific features of mathematics that no other science can share. The talk will be accessible to anybody, no mathematical knowledge is required.
02.02.2010 13:00
Jiri Svoboda
Astronomical Institute, Academy of Sciences, Prague
Role of emission angular directionality in spin determination of accreting black holes with a broad iron line
Abstract
Jiri Svoboda
Role of emission angular directionality in spin determination of accreting black holes with a broad iron line
Spin of an accreting black hole can be determined by spectroscopy of the emission and absorption features produced in the inner regions of an accretion disc. In this talk we will discuss the method employing the relativistic line profiles of iron in the X-ray domain, where the emergent spectrum is blurred by general relativistic effects. We study how sensitive the spin determination is to the assumptions about the intrinsic angular distribution of the emitted photons. The uncertainty of the directional emission distribution translates to 20% uncertainty in determination of the marginally stable orbit.
