Disputas: Dag Sverre Seljebotn

M. Sc. Dag Sverre Seljebotn ved Institutt for teoretisk astrofysikk vil forsvare sin avhandling for graden ph.d.: Computational techniques for efficient Bayesian analysis of the Cosmic Microwave Background.

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  • Senior Research Associate Mark Ashdown, Kavli Institute for Cosmology, Institute of Astronomy, University of Cambridge, UK (opponent)
  • Academy Research Fellow Elina Keihänen, Department of Physics, University of Helsinki, Finland (opponent)
  • Associate Professor Sijing Shen, Institute of Theoretical Astrophysics, University of Oslo (administrator)

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Populærvitenskapelig sammendrag av avhandlingen

Dag Sverre Seljebotn har utviklet nye, effektive beregningsmetoder for analyse av den kosmiske bakgrunnstrålingen. Takket være disse kan vi for første gang utføre en eksakt analyse av bildene fra romteleskopet Planck på full oppløsning.


We present new, efficient algorithms for analysis of the Cosmic Microwave Background (CMB). By applying these algorithms it is possible, for the first time, to carry out an exact analysis of the images from the Planck space observatory on full resolution.

The Planck space observatory was launched in 2009 and has provided us with extremely high resolution images of the microwave radiation in the universe. Previously, it was not possible to do an exact analysis of these images on full resolution due to the computational effort required. Thanks to the faster methods presented in Dag Sverre Seljebotn’s PhD thesis, full resolution analysis of these images has now become possible.

Analysis of the CMB is a cornerstone of modern cosmology. However, the Milky Way emits microwave radiation that obscures the CMB signal. The first part of the PhD is a better algorithm to separate out and remove this galactic radiation, so that we can get a better view of the CMB behind our galaxy.

The second part of the PhD is research on how to more efficiently compute the so-called “spherical harmonic transform”; a computational tool employed in many situations where one deals with data or images on a sphere. Thus this work finds applications not only in astrophysics, but also meteorology, geophysics, and so on. Some of these computational improvements are now in use by thousands of researchers every day.

Publisert 22. jan. 2018 11:15 - Sist endret 22. jan. 2018 11:19