In between the Cosmic Microwave Background (CMB) and the instrument there are other sources of radiation, called foregrounds. The foregrounds radiate in the same frequency bands as the background, and cause contamination ...

Observations of the Cosmic Microwave Background is impaired by other astrophysical sources that also radiate in the microwave spectrum. These other, non-CMB sources are known as foregrounds. In this thesis, three different ...

I have investigated the total energy of Friedmann-Robertson-Walker universes. This is an interesting issue, because if the energy of the universe turns out not to be conserved, it will be in conflict with our common ...

It is believed that the Broad Emission Line Region of Quasars consists of discrete clouds. Due to the suspected small size of a cloud, the radiation from clouds may be strongly amplified by gravitational microlensing. It ...

Five years (1992-1997, ~2650 images) of optical observations of the gravitational lens system QSO 0957+561 were analyzed using a new photometry package developed by Jan Teuber and me. My supervisor was Prof. Rolf Stabell, ...

In-situ observations together with spectroscopic measurements show that the elemental abundance in the solar atmosphere varies from the photosphere to solar wind. An enrichment for low First Ionisation Potential elements ...

The solar chromosphere has previously been thought to be a homogenic layer of the solar atmosphere, but better observations have made it evident that the chromosphere is a highly dynamic area. Spicules are structures ...

Observations of how matter is distributed on different length scales in the universe are an important test of cosmological models. For example, such observations can give an upper limit for the mass of neutrinos: As the ...