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O usodi zvezd po plimskem raztrganju
ID Jankovič, Taj (Author), ID Gomboc, Andreja (Mentor) More about this mentor... This link opens in a new window

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Abstract
V središčih večine galaksij se nahajajo supermasivne črne luknje z masami $10^5$--$10^{9,5}$$\,\mathrm{M_\odot}$, ki jih obdajajo središčne kopice zvezd. Po ocenah se s pogostostjo $10^{-5}$--$10^{-4}$/galaksijo/leto zgodi, da katero od zvezd zanese v bližino črne luknje in jo le-ta raztrga s svojo plimsko silo. Po raztrganju ima zvezdna snov pozitivno ali negativno celotno energijo, kar odloča o njeni usodi. Ostanki snovi s pozitivno energijo so nevezani in pobegnejo iz gravitacijskega potenciala črne luknje. Snov z negativno celotno energijo se vrne v bližino črne luknje, kjer tvori okoli nje disk, ki še nekaj mesecev ali let oddaja svetlobo. Ključnega pomena pri razumevanju plimskih raztrganj zvezd, nastanka diskov in njihov svetlobnih krivulj, je poznavanje količine snovi, ki konča v črni luknji, se nabere v disku ali pa pobegne v medzvezdni prostor. V magistrskem delu sem numerično modeliral plimsko raztrganje zvezd. Simulacije plimskega raztrganja sem opravil s programom PHANTOM, ki temelji na metodi hidrodinamike zglajenih delcev. Pri računanju gravitacijskega polja supermasivne črne luknje sem upošteval relativistične popravke k Newtonovem potencialu. Izvedel sem podrobnejšo analizo dinamike zvezdne snovi po raztrganju. Osredotočil sem se na masni delež vezane in nevezane snovi ter njuno časovno odvisnost. Izračune sem izvedel za Soncu podobne zvezde na različnih vrstah tirnic (eliptične, parabolične, hiperbolične) in različne vrednosti vpadnega faktorja.

Language:Slovenian
Keywords:plimsko raztrganje, črna luknja, hidrodinamika zglajenih delcev, posplošeni Newtonov potencial, vezana in nevezana snov
Work type:Master's thesis/paper
Typology:2.09 - Master's Thesis
Organization:FMF - Faculty of Mathematics and Physics
Year:2019
PID:20.500.12556/RUL-110407 This link opens in a new window
COBISS.SI-ID:3370340 This link opens in a new window
Publication date in RUL:14.09.2019
Views:1221
Downloads:198
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Secondary language

Language:English
Title:On the fate of stars after a tidal disruption event
Abstract:
Majority of galactic centers contain a supermassive black hole (mass $10^5$--$10^{9,5}\,$$\mathrm{M_\odot}$), surrounded by a central stellar cluster. There is a probability of $10^{-5}$--$10^{-4}$ /galaxy/year that a star from such a cluster is scattered and brought in the proximity of the black hole, where it is disrupted by black hole's tidal force. Fate of the stellar debris depends on its total energy. Parts of the debris with positive energy are unbound and escape from the gravitational potential of the black hole. On the other hand, debris with negative total energy is bound and returns in the black hole's vicinity, where it forms an accretion disk, which may emit radiation for months to years. A key issue in understanding stellar tidal disruption events, disk formation and their light curves, is the amount of matter, which either falls in the black hole, forms a disk or escapes in the interstellar space. In my master's thesis I numerically modeled tidal disruption events. Simulations of tidal disruption events were done with the PHANTOM code, which is based on smoothed particle hydrodynamics method. In the calculations of the supermassive black hole's gravitational field I took into account relativistic corrections to the Newtonian potential. I carried out an analysis of the stellar debris after disruption. I focused on the mass fraction of the bound and unbound matter as well as their temporal dependance. Computations were performed for different types of trajectories (elliptic, parabolic, hyperbolic) and for different values of the penetration factor.

Keywords:tidal disruption event, black hole, smoothed particle hydrodynamics, generalized Newtonian potential, bound and unbound debris

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