Graduate theses
Current Record: 17 of 195
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Title |
Astrophysical consequences of phase transition in millisecond pulsars |
Alternative Title |
Αστροφυσικές συνεπείς της αλλαγής φάσης σε πάλσαρ του χιλιοστού του δευτερολέπτου |
Author
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Ασπραδάκης, Νικόλας
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Thesis advisor
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Αντωνιάδης, Γιάννης
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Abstract |
In a low mass binary system with a neutron star as the primary star and a star in the main sequence
phase as its companion, after the end of the accretion process, where we have a MSPs-WD system, the
orbit due to tidal forces should be almost circular with eccentricity equal to zero. However the observations
of some eccentric binaries have shown that something making the system to have a more elliptical orbit
with e ≃ 0.1. The explanation we will try to give here is based on the theory of strange stars and the
phase-transition from baryonic matter to quark matter which causes an asymmetric kick that disrupts the
system and changes the eccentricity of the orbit. We want to have a better understanding to what is the
relationship between the the mass and radius of a neutron star in order to have the phase-transition from
the different layers of the pulsar’s core.
In order for us to investigate this phenomena, we will use a software program called MESA, that can
simulate the stellar evolution of a star, or in our case a binary system of a neutron star and a main sequence
star that will eventually evolve in a millisecond pulsar-white dwarf system. This simulation will provide
us with information regarding the quantities that we are interested (mass, radius, spin period etc). After
collecting the necessary data, we will import them to the evolution code concerning the spin evolution, the
mass transfer process and the accretion torque mechanism that we wrote on using python, we proceeded
with further analysis for this project.
In the first chapter we present a thorough theoretical background about stellar evolution, binary evolution
and phase transition from baryonic matter to quark matter. At the end of this chapter there will be a brief
talk about the purpose of the thesis. In the second chapter we discuss about the numerical tools and the
code about the evolution of the binary we want to study through the simulation that MESA can provide.
There will be a discussion about the polytropic equation of state that we choose to use, the evolution of
angular momentum, the spin evolution and the parameters we used. We will also analyze the accretion
process and torque provided by both Tauris and Bhattacharyya. In the third chapter we will present the
results of this analysis and compare the different cases we chose to study. To finish the thesis, in the final
chapter we present the conclusions regarding the project and a brief discussion about future projects and
changes to make the analysis more clear and correct problematic parts.
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Language |
English |
Issue date |
2024-03-29 |
Collection
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School/Department--School of Sciences and Engineering--Department of Physics--Graduate theses
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Type of Work--Graduate theses
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Permanent Link |
https://elocus.lib.uoc.gr//dlib/f/e/0/metadata-dlib-1709210382-522850-7293.tkl
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Views |
109 |