Some finished and ongoing projects

Data analysis

Ozone data from Iceland was analysed in 1991-1992 using simple parametric models. We found that more detailed methods were needed and an attempt at scrutinizing the data was made recently by using a relatively new spectral estimation technique, the multiple taper method. We have also investigated the coherency between solar UV radiation and equatorial total ozone. I've worked on this project in collaboration with Guðmundur Bjarnason.

Through collaboration with Sigfús Johnsen, I was also somewhat involved in the application of the mtm to icecore data from Greenland.

Some while ago I gave a talk on the mtm. In my spare time, I have looked into the possibility of making the mtm more robust by using bootstrap techniques to find the significance levels of harmonic components, and to construct confidence intervals for the estimated parameters and spectrum. Some of these techniques were utilized in the paper on coherency between solar UV radiation and equatorial total ozone.

Astrophysics

During my B.Sc. studies I worked together with my professor Einar Guðmundsson on a simple problem in classical cosmology. The results were published in MNRAS, vol. 246.

The equation of state for matter in a high magnetic field (presumably the conditions in the crusts of neutron stars) was calculated using the Thomas-Fermi approximation in a paper together with Einar Guðmundsson, Jakob Yngvason, Chris Pethick, and Ikko Fushiki. This work has now been extended to take into account the effects of non-zero temperature; Our results were published in the August 1 issue of ApJ, but the paper is also available as a sissa preprint.

Astronomical observations

I am involved in a project which aims at measuring masses of galaxy clusters from lensing effects on background galaxies. This is the first icelandic observational project on the Nordic Optical Telescope after Iceland joined the NOT collaboration in 1997. Our first attempt was at CL0024+1654 in October 1997, the weather teased us so we only partially succeeded. You can read about the results on Lars Lindeberg Christensen's excellent page which also gives some background for the method.

In May 1998, we (I and Vilhelm S. Sigmundsson) observed the X-ray selected cluster MS1621+2640, You will find more information here. I gave a talk (in icelandic) on our observations of MS1621 and preliminary results in January 1999. Further observations were done on the rich cluster Cl0024+1654 in August 1999, the results on depletion of background galaxies will be reported on in a forthcoming paper. As a spin-off we are now planning further observations to study the color-magnitude diagram for galaxy clusters and how it links up with the evolution of clusters.