From PoGOLite to PoGO+

As avid readers of this blog, you no doubt remember PoGOLite - a balloon-borne hard X-ray polarisation mission which is part of the Swedish National Space Board national programme for balloon and sounding rocket research at the Esrange Space Centre. After a number of frustrating set-backs (broken balloons, bad weather, ...), the Crab was successfully observed in July 2013 - providing the first measurement of the polarisation of emissions in the 20 - 120 keV energy band. Technical difficulties encountered during the flight meant that the polarisation parameters could only … Continue Reading ››

Measuring the supernova rate in the early Universe by using galaxy clusters as gravitational telescopes

Supernovae are very rare phenomena in the Universe and their transient nature made them difficult to find for a long time. So, it is not surprising that the discovery rate was around two supernovae per month 30 years ago. Today, we are able to find supernovae daily. For example, the Intermediate Palomar Transient Factory, in which our group at the Oskar Klein Centre is involved, has discovered almost 3000 supernovae in the last few years. However, these supernovae are all relatively nearby, since the survey is not sensitive … Continue Reading ››