Presentasjon av masteroppgave: Renate Mauland
Quantized Vortices in Superfluid Dark Matter
In a recent paper by Berezhiani and Khoury , a superfluid dark matter (DM) model was presented. The model consists of light axion-like DM particles (m ~ eV), which condense and form a superfluid at galactic scales. The superfluid exhibits collective excitations known as phonons, which interact with baryons and mediate a force similar to that of Modified Newtonian Dynamics (MOND). The superfluid DM model therefore combines the success of MOND at small scales with that of the ΛCDM model at large scales. By analogy with superfluids studied in the lab, we expect a grid of vortices with quantized circulation to form in a rotating galaxy containing superfluid DM. In this thesis, we explore the properties of the superfluid DM vortices and their impact on the surroundings. We find that the vortex cores are small, 10-4 - 10-3 m, and that the vortices are separated by vast distances,~ 0.002AU. The viable parameter space of the model is found to be substantial, and a reduction in the DM particle mass results in larger vortices with a higher energy. Yet, no combination of parameters explored here give vortices energetic enough to have a noticeable effect on the galaxy as a whole. However, we find that the baryons might affect the vortices instead, although further investigation is needed to understand the full extent of this result. As a first step towards a more complete model, we also extract a vortex equation from the relativistic Lagrangian describing the model. We find that a solution with the standard properties assumed for a vortex solution is unlikely to exist, at least for the parameter scales proposed in .
Veileder: Professor Øystein Elgarøy, Institutt for teoretisk astrofysikk, UiO
Intern sensor: Professor David F. Mota, Institutt for teoretisk astrofysikk, UiO
Ekstern sensor: Professor Sigbjørn Hervik, Institutt for matematikk og fysikk, UiS