Presentasjon av masteroppgave: Gustav Bredal Erikstad

Astrophysical Archaeology: Reviving COBE–DIRBE for Next-Generation Global Analysis


This thesis aims to revive the data gathered by the Diffuse Infrared Background Experiment (DIRBE) aboard the COsmic Background Explorer (COBE) satellite, and, through modernizing this dataset, make it available for future Cosmic Microwave Background (CMB) research. The value of the DIRBE dataset in cosmological research is explained and defined, and its importance to component separation and global CMB analysis is highlighted. The original dataset is described before the process of reformatting the Calibrated Individual Observations (CIO), stored in FITS files, into new Time Ordered Data (TOD) in a modern Hierarchical Data Format (HDF5) is explained in some detail. The methods applied during the work of this thesis are explained in order to make the results reproducible and to document the new TOD, so that future work may build on this foundation. To verify the methods and results produced by this thesis, 10 full-sky intensity maps, and 6 polarimetry maps, with a pixel size of 27 ′ are made from the TOD. The intensity maps are compared to those made by the Centre d’Analyse de Données Etendues (CADE) through relative difference maps and linear regression on the temperature in both map’s pixels. The maps produced by this thesis are comparable to those made by CADE to within 17%. In addition, full-sky maps of the average polarization signal Y are produced for the 1.25 µm, 2.2 µm and 3.5 µm polarimetry bands. These are likely the first of their kind, as [Berriman et al., 1994] published Y maps containing only 6 days of observations.

This is a hybrid examination. Participants can join in person (Peisestua 304) or by zoom link. 



Professor Ingunn K. Wehus, Institute of Theoretical Astrophysics, UiO (main-supervisor)

Doctoral Research Daniel C. Herman, Institute of Theoretical Astrophysics, UiO (co-supervisor)

Postdoctoral Duncan Watts, Institute of Theoretical Astrophysics, UiO (co-supervisor)

Intern. assessor: Professor David Fonseca Mota, Institute of Theoretical Astrophysics, UiO 

Extern. assessor: Tenured research Mathieu Remazailles, Institute of Physics of Cantabria 

Publisert 18. mai 2022 09:53 - Sist endret 8. juni 2022 11:30