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Evolution of the stellar disc in the Galactic centre
Kobrle, Stanislav ; Šubr, Ladislav (advisor) ; Karas, Vladimír (referee)
In this thesis we will study dynamical models of Galactic centre analyse them and compare with available observational data. Our main target is to investigate origin of young stars which are being observed here. We examine if they could have been born in a single accretion disc. Next target is to confirm or disprove the possibility of existence one or more disc-like structures which are frequently discussed by scientists. We introduce methods used to detect stellar structures and apply them to artificial and observational data.
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Binary pulsars - astrophysical laboratories (not only) of theory of general relativity
Beňová, Zuzana ; Kofroň, David (advisor) ; Karas, Vladimír (referee)
Title: Binary pulsars - astrophysical laboratories of general relativity Author: Zuzana Beňová Department: Institute of Theoretical Physics Supervisor: Mgr. David Kofroň, PhD Supervisor's e-mail address: d.kofron@gmail.com The mail concern of this work are tests of relativistic theories of gravitation (mainly GR) that are made by employing compact double-pulsars. The first part is devoted to basic tests and effects of relativistic theories: gravitatio- nal redshift, orbital period decay due to the emission of gravitational waves, periastron shift, Shapiro effect and precession of rotation axis. A brief de- scription of pulsars (in general) and double-pulsars follows. We describe the orbital parameters and their post-Keplerian corrections. Finally, the theory is demonstrated on the unique double-pulsar PSR J037-3039 A/B which was discovered only 7 years ago. Keywords: relativistic theories, double pulsar, tests of GR
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Magnetické pole v jádru Galaxie
Hamerský, Jaroslav ; Karas, Vladimír (advisor) ; Kovář, Jiří (referee)
In the present work we study the properties of accretion tori orbiting black hole. Our approach to this problem comes from the solving of general relativistic magnetohydrodynamic equations, which follow from conservation of the energy-momentum tensor, the particle number and from Maxwell's equations. We solve these equations by numerical methods which are described in Chapter 1. The formalism of tori which we consider here is described in Chapter 2. We are interested in tori with constant density of angular momentum and Fishbone-Moncrief tori mainly. We study accretion rates in these tori when the mass of black hole is increased suddenly and so the equilibrium in the torus is corrupted. For tori with constant density of angular momentum we study the influence of the presence of toroidal magnetic field on accretion rates.
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Vliv silného gravitačního pole kompaktních objektů na jejich záření
Sochora, Vjačeslav ; Karas, Vladimír (advisor) ; Schee, Jan (referee)
In the present work we describe different cosmic systems that contain the compact objects (neutron stars or black holes). The accretion of the matter on the compact object is a main source of the radiation and that is why we consider several models of accretion. The energy of emitted radiation is different from the observed energy due to the gravitational redshift and the Doppler shift. We are interested in the minimum and maximum values of this change of emitted radiation. We show how to calculate these extremes in Kerr metric by the help of the elliptic integrals assuming that the emission radius, the angular momentum of black hole, and the inclination angle of the observer are given.
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