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Hysteresis behavior of shocks in low angular momentum flows
Suková, Petra
In this work we present the GRMHD 1D simulations of accreting matter with variable angular momentum. We focus on the existence and behaviour of the shock in the flow. We show that the location of the shock front responds to the change of the angular momentum, which also causes the accretion rate onto the black hole to vary on different time scales. We study the possible hysteresis behaviour of the shock\nfront during the time evolution of the flow. We discuss the potential observational effects of this phenomenon.
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Geodesics in the field of a perturbed black hole: where appears chaos?
Polcar, Lukáš ; Semerák, Oldřich (advisor) ; Suková, Petra (referee)
It is widely known that the motion around Schwarzshild black hole is completely integrable. However, after adding a disc or a ring one of the symmetries of the system is broken and the motion may become chaotic for some values of parameters. The aim of this thesis is to identify where appears chaos in static, axially symmetric spacetime by using the geometrical method based on the geodesic deviation equation. Is it possible to predict chaotic behaviour in general relativity solely from local geometrical properties of spacetime, without explicitly solving the geodesic equation? Powered by TCPDF (www.tcpdf.org)
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Chaotic Motion around Black Holes
Suková, Petra
As a non-linear theory of space-time, general relativity deals with interesting dynamical systems which can be expected more prone to chaos than their Newtonian counter-parts. In this thesis, we study the dynamics of time- like geodesics in the static and axisymmetric field of a Schwarzschild black hole surrounded, in a concentric way, by a massive thin disc or ring. We reveal the rise (and/or decline) of geodesic chaos in dependence on parameters of the sys- tem (the disc/ring mass and position and the test-particle energy and angular momentum), (i) on Poincaré sections, (ii) on time series of position and their power spectra, (iii) by applying two simple yet powerful recurrence methods, and (iv) by computing Lyapunov exponents and two other related quantifiers of or- bital divergence. We mainly focus on "sticky" orbits whose different parts show different degrees of chaoticity and which offer the best possibility to test and compare different methods. We also add a treatment of classical but dissipative system, namely the evolution of a class of mechanical oscillators described by non-standard constitutive relations.
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Chaotic Motion around Black Holes
Suková, Petra ; Semerák, Oldřich (advisor) ; Šubr, Ladislav (referee) ; Loukes-Gerakopoulos, Georgios (referee)
As a non-linear theory of space-time, general relativity deals with interesting dynamical systems which can be expected more prone to chaos than their Newtonian counter-parts. In this thesis, we study the dynamics of time- like geodesics in the static and axisymmetric field of a Schwarzschild black hole surrounded, in a concentric way, by a massive thin disc or ring. We reveal the rise (and/or decline) of geodesic chaos in dependence on parameters of the sys- tem (the disc/ring mass and position and the test-particle energy and angular momentum), (i) on Poincaré sections, (ii) on time series of position and their power spectra, (iii) by applying two simple yet powerful recurrence methods, and (iv) by computing Lyapunov exponents and two other related quantifiers of or- bital divergence. We mainly focus on "sticky" orbits whose different parts show different degrees of chaoticity and which offer the best possibility to test and compare different methods. We also add a treatment of classical but dissipative system, namely the evolution of a class of mechanical oscillators described by non-standard constitutive relations.
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Solving test-particle equations of motion near a black hole
Ryston, Matěj ; Ledvinka, Tomáš (advisor) ; Suková, Petra (referee)
Bachelor thesis Matěj Ryston 2011/2012 Abstract in English This work aims to give a well-arranged summary of the description and solving the equations of motion of particles outside a black hole (a star) with emphasis on numerical solutions. For that purpose a summary of numerical methods for solving ordinary differential equations, together with a review and comparison of chosen methods, is given. In the second chapter follows a brief recall of the foundations of General Relativity as well as the description of the geometry of Schwarzschild solution of the Einstein equations. After that equations of motion are formulated. In conclusion, selected numerical methods are used on solving said equations of motion of a test particle or those describing bending of light rays in closeness to a black hole.
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Chaos in motion around black holes
Suková, Petra ; Semerák, Oldřich (advisor) ; Šubr, Ladislav (referee)
The geodesic motion around Kerr black holes is regular, but this may change when an additional source is present, even if the space-time symmetry were not lowered. In this thesis we study the eect of a simple (static and axially symmetric) additional source on geodesic dynamics in the eld of a Schwarzschild black hole. In the static case the complete space-time can be described by an exact solution of Einstein equations thanks to a relatively simple superposition of the central-black-hole and the external-source metrics. Following the astrophysical motivation, we will specically consider, as the external source, the thin ring (linear source) of the Bach-Weyl type and innite thin discs (planar sources) of several types (inverted counter-rotating discs of Morgan and Morgan and the discs with power-law radial shape of density). The results may be relevant e.g. for a long-term behaviour of discrete sources (stars) in the eld of a very massive black hole in a galactic nucleus, surrounded by an accretion disc and/or by a massive toroid.
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Determination of antibiotics in the wastewater
Suková, Petra ; Tulková, Tereza (referee) ; Vávrová, Milada (advisor)
This thesis deals with problem of antibiotics, substances used in the prevention and treatment of infectious diseases in human and veterinary medicine. Have been discussed aminopenicillins antibiotics from the group of antibiotics, particularly ampicillin and amoxicillin, which are one of the most frequently prescribed antibiotics in both the Czech Republic and in the world now. Drug substances together with wastewater pass into the wastewater treatment plant where sewage process does not remove the drug from the treated water entirely. Drug substances can be penetrate into the other components of the environment in the result, especially in surface water and soil, where they can have adverse effects on organisms living there. For the isolation of analytes from samples of wastewater was selected solid phase extraction (SPE). For final analysis of antibiotics was used method of ultra-high performance liquid chromatography with UV-VIS detection with diode array detector and method of liquid chromatography with mass spectrometric detection. Based on the optimization of analytical techniques was especially ampicillin chosen as analyte isolated from the matrix of waste water. Analysis of the wastewater was conducted for a total of four days of influent and effluent wastewater treatment plant in Brno-Modřice and wastewater treatment plant which is situated in area of the Veterinary and Pharmaceutical University in Brno.
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