Presentasjon av masteroppgave: Sara Clausen Jønvik

Testing quadru- and octopolar asymmetry in Planck data.


We perform an investigation of quadru- and octopolar asymmetry in the CMB data by expanding the on the study of alignment and angular clustering of the dipole components of the CMB power distribution across multipoles l = 2 to l = 1500, as done in section 6.5 in the 2015 Planck isotropy article Ade et al. (2016c). We develope a routine that is able to extract the underlying spherical harmonic coefficient of a masked map, up to l = 3. The direction of the quadrupole and octoplar components are defined as in de Oliveira-Costa et al. (2004) and a pseudo-Rayleigh statistic is used to estimate the significance of the clustering as the portion of simulations based on the ΛCDM model that exhibit a clustering greater than the observational data. We find no significant clustering in neither the quadrupole or the octople. A correlation analysis is also performed in order to avoid the problems arising from the definition of direction in the quadrupole and octopole. This analysis does not find a significant clustering in the dipole, in tension with the results published in Ade et al. (2016c), but detects a tentative clustering in the octopole. Investigations with larger number of simulations are needed in order to better assess the accuracy of the results found here.


Veileder: Professor Frode Kristian Hansen, Institutt for teoretisk astrofysikk, UiO

Intern sensor: Førsteamanuensis Boris Vilhelm Gudiksen, Institutt for teoretisk astrofysikk, UiO

Ekstern sensor: Forsker Elina Kaihänen, University of Helsinki, Department of Physics

Publisert 21. sep. 2017 09:53 - Sist endret 21. sep. 2017 09:53