Abstract
Precise modelling of foreground emission is crucial to extract the Cosmic microwave background (CMB) signal. Recent developments in the hunt for primordial B-modes in the polarized CMB favor component separation to be done directly in the time- ordered domain to minimize foreground contamination and systematic effects. This would require all aspects of component separation to become more efficient due to an unavoidable increase in data volume.
In this thesis, we implement an efficient and accurate method of performing Zodiacal corrections to high-frequency cosmological data, directly in the time-ordered domain. We adopt the Kelsall et al. (1998) interplanetary dust (IPD) model consisting of six Zodiacal components - a Diffuse Cloud, three Dust Bands, a Circumsolar Ring, and the Earth-trailing Feature. We compute the Zodiacal emission by integrating the dust density along a line-of-sight from an observer to 5.2 AU, pixel-by-pixel at the time of observation, similar to the approach used by the Planck collaboration.
Our model is tested using the BeyondPlanck LFI data processing pipeline from which we have obtained maps that accurately reproduce the Zodiacal emission templates used during the Planck Zodiacal corrections. The results obtained by our model suggests that the Zodiacal emission is slightly weaker than previously estimated by Planck, most notably for the Diffuse Cloud, which is found to differ by ∼ 8% in overall signal amplitude, although further investigation is needed to fully understand the extent of this result along with a new fit of the Zodiacal emissivities. As a possible step towards a more precise IPD model, we test the significance of dust enhancements to the Circumsolar Ring at the Sun-Earth Lagrange points L4 and L5. We find that enhancements at the order of the Earth-trailing Feature show no significant increase to the overall signal. Future work to make the method more efficient and possible improvements to the K98 IPD model are also described here.
Veileder: Professor Ingunn Kathrine Wehus, Institutt for teoretisk astrofysikk, UiO
Medveileder: Professor Hans Kristian Kamfjord Eriksen, Institutt for teoretisk astrofysikk, UiO
Intern sensor: Professor David Fonseca Mota, Institutt for teoretisk astrofysikk, UiO
Ekstern sensor: Førsteamanuensis Jostein Riiser Kristiansen, OsloMet