Tensor virial analysis and magnetic field perturbations of magnetized molecular cloud cores

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dc.contributor.authorFranzmann, Erica
dc.contributor.examiningcommitteeSafi-Harb, Samar (Physics and Astronomy)en_US
dc.contributor.examiningcommitteeShamseddine, Khodr (Physics and Astronomy)en_US
dc.contributor.examiningcommitteeLeung, Carson (Computer Science)en_US
dc.contributor.examiningcommitteeMatzner, Christopher (University of Toronto)en_US
dc.contributor.supervisorFiege, Jason
dc.date.accessioned2023-01-13T22:17:32Z
dc.date.available2023-01-13T22:17:32Z
dc.date.copyright2023-01-04
dc.date.issued2023-01-04
dc.date.submitted2023-01-04T22:04:46Zen_US
dc.degree.disciplinePhysics and Astronomyen_US
dc.degree.levelDoctor of Philosophy (Ph.D.)en_US
dc.description.abstractWe present a detailed analysis of the three-axis stability of molecular cloud core model geometries and the effects of three-dimensional magnetic field perturbations on simulated polarization maps. We have previously developed a molecular cloud core modelling package called “PolCat”, which generates three-dimensional models of density and magnetic field structures constrained by reduced χ2 fits to submillimetre polarization and continuum intensity data. PolCat fits provide insight into the underlying structures of cores, and by extension, the initial conditions from which stars form. The most commonly applied form of the virial theorem in an astrophysical context is the scalar form, with relatively few applications of the full tensor form. We have found through examination of the three-axis virial equilibria not only the expected families of spheroidal geometries, but also families of triaxial ellipsoid geometries. In application as a PolCat stability check, we allowed our models to be slightly out of tensor equilibrium. We performed tests with both synthetic data and data of the OMC-1 BN/KL region from the SCUPOL Legacy Catalogue and BISTRO survey. We found that the virial criterion eliminated models with unrealistic geometries. Additionally, magnetic field strength estimates from the virial fits were in good agreement with independent measurements of the region. A common method to estimate magnetic field strengths from polarization is the Chandrasekhar-Fermi method, where deflections of B-field polarization vectors from an assumed large-scale structure are assumed to directly equate to Alfvénic perturbations in the underlying magnetic field. However, a limitation of this method is that polarization maps are two-dimensional projections of three-dimensional structures, and the traced large-scale field may not be truly representative of the underlying structure. To examine the how three-dimensional perturbations would affect the polarization maps, we developed a method to propagate Alfvén waves along PolCat models’ curved magnetic field lines and compared the perturbed and unperturbed maps. After perturbing our models with both individual and cumulative single-mode Alfvén waves, we find that patterns of deflection are highly dependent on the inclination of the magnetic field to the line of sight, and each model geometry has a characteristic pattern of deflection.en_US
dc.description.noteFebruary 2023en_US
dc.description.sponsorshipSir Gordon Wu Graduate Scholarshipen_US
dc.identifier.urihttp://hdl.handle.net/1993/37109
dc.language.isoengen_US
dc.rightsopen accessen_US
dc.subjectMolecular Cloudsen_US
dc.subjectAstrophysicsen_US
dc.subjectModellingen_US
dc.subjectStabilityen_US
dc.subjectvirial theoremen_US
dc.subjectAlfvén wavesen_US
dc.subjectStar formationen_US
dc.subjectSubmillimetre polarizationen_US
dc.subjectMHDen_US
dc.subjectmagnetohydrodynamicsen_US
dc.subjectISMen_US
dc.subjecttensor virial theoremen_US
dc.subjectAlfvén wave propagationen_US
dc.titleTensor virial analysis and magnetic field perturbations of magnetized molecular cloud coresen_US
dc.typedoctoral thesisen_US
local.subject.manitobanoen_US
oaire.awardTitleAlexander Graham Bell Canada Graduate Scholarships - Doctoralen_US
oaire.awardURIhttps://www.nserc-crsng.gc.ca/students-etudiants/pg-cs/cgsd-bescd_eng.aspen_US
project.funder.identifierhttps://doi.org/10.13039/501100000038en_US
project.funder.nameNatural Sciences and Engineering Research Council of Canadaen_US
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