Magnetic fields in and around galaxies
<p>Magnetic fields are an ubiquitous component of our Universe. They are expected to play an important role in the evolution of many astrophysical systems, from molecular clouds to galaxy clusters. In the case of galaxies, magnetic energy is measured to be in equipartition with thermal and tur...
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| Format: | Thèse |
| Langue: | English |
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2019
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| _version_ | 1826286142715068416 |
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| author | Martin, S |
| author2 | Devriendt, J |
| author_facet | Devriendt, J Martin, S |
| author_sort | Martin, S |
| collection | OXFORD |
| description | <p>Magnetic fields are an ubiquitous component of our Universe. They are expected to play an important role in the evolution of many astrophysical systems, from molecular clouds to galaxy clusters. In the case of galaxies, magnetic energy is measured to be in equipartition with thermal and turbulent energies of the interstellar medium. Despite this omnipresence, the origin of cosmic magnetic fields remains an open question, and the precise influence that magnetic fields have in shaping the formation and evolution of galaxies is uncertain. </p> <p>Using magnetohydrodynamical numerical simulations of both cosmological volumes and high-resolution cosmic zoom-ins on individual galaxies, I explore in this thesis the main mechanisms likely to generate galactic magnetic fields similar to those observed and the role these latter play in shaping galaxies. I present various extensions to existing numerical techniques to account for magnetism in state-of-the-art software employed to simulate galaxies. These culminate in the introduction of a new algorithm that traces magnetic fields generated by different sources separately. In particular, I simulate the formation of a Milky Way-like galaxy, magnetised either through dynamo amplification, a strong primordial magnetic field, or magnetised stellar feedback, demonstrating that each mechanism is capable of producing realistic levels of magnetisation on its own. Jointly tracing primordial and stellar generated fields, I study how they compete to produce the total magnetic field. I find a large degree of interaction, both inside galaxies, where the two components contribute significantly to the magnetic energy budget, and around galaxies, where the magnetic fields pushed out by stellar feedback pollute the primordial magnetic field. In a final set of simulations, I explore how magnetic fields modify the global properties of a galaxy, finding evidence of morphological compression and braking of the rotation of the galaxy by strong magnetisation.</p> |
| first_indexed | 2024-03-07T01:39:23Z |
| format | Thesis |
| id | oxford-uuid:96554453-2844-450c-8815-3d1683be867d |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T01:39:23Z |
| publishDate | 2019 |
| record_format | dspace |
| spelling | oxford-uuid:96554453-2844-450c-8815-3d1683be867d2022-03-26T23:52:12ZMagnetic fields in and around galaxiesThesishttp://purl.org/coar/resource_type/c_db06uuid:96554453-2844-450c-8815-3d1683be867dAstrophysicsEnglishORA Deposit2019Martin, SDevriendt, JSlyz, A<p>Magnetic fields are an ubiquitous component of our Universe. They are expected to play an important role in the evolution of many astrophysical systems, from molecular clouds to galaxy clusters. In the case of galaxies, magnetic energy is measured to be in equipartition with thermal and turbulent energies of the interstellar medium. Despite this omnipresence, the origin of cosmic magnetic fields remains an open question, and the precise influence that magnetic fields have in shaping the formation and evolution of galaxies is uncertain. </p> <p>Using magnetohydrodynamical numerical simulations of both cosmological volumes and high-resolution cosmic zoom-ins on individual galaxies, I explore in this thesis the main mechanisms likely to generate galactic magnetic fields similar to those observed and the role these latter play in shaping galaxies. I present various extensions to existing numerical techniques to account for magnetism in state-of-the-art software employed to simulate galaxies. These culminate in the introduction of a new algorithm that traces magnetic fields generated by different sources separately. In particular, I simulate the formation of a Milky Way-like galaxy, magnetised either through dynamo amplification, a strong primordial magnetic field, or magnetised stellar feedback, demonstrating that each mechanism is capable of producing realistic levels of magnetisation on its own. Jointly tracing primordial and stellar generated fields, I study how they compete to produce the total magnetic field. I find a large degree of interaction, both inside galaxies, where the two components contribute significantly to the magnetic energy budget, and around galaxies, where the magnetic fields pushed out by stellar feedback pollute the primordial magnetic field. In a final set of simulations, I explore how magnetic fields modify the global properties of a galaxy, finding evidence of morphological compression and braking of the rotation of the galaxy by strong magnetisation.</p> |
| spellingShingle | Astrophysics Martin, S Magnetic fields in and around galaxies |
| title | Magnetic fields in and around galaxies |
| title_full | Magnetic fields in and around galaxies |
| title_fullStr | Magnetic fields in and around galaxies |
| title_full_unstemmed | Magnetic fields in and around galaxies |
| title_short | Magnetic fields in and around galaxies |
| title_sort | magnetic fields in and around galaxies |
| topic | Astrophysics |
| work_keys_str_mv | AT martins magneticfieldsinandaroundgalaxies |