Tag Archives: X-ray

The Fermi symposium 2011: AGNs, pulsars and gamma ray bursts

The results presented at the III Fermi symposium in Rome reflected, in particular, what a magnificent instrument the Fermi LAT is for observing active galactic nuclei and pulsars. The 2 source catalogue 2FGL was presented and will soon be released with 1888 sources. Much attention was given to the blazar 3C454.3 which has been monitored since the launch and has undergone a series of very bright outbursts. The multiwavelength analysis by Stefan Larsson revealed a far more complex behaviour than expected in the simple picture we had of AGN jets before the launch of Fermi. The discovery of spectral breaks at GeV energies was nicely interpreted by the former Stockholm astronomer Juri Poutanen and collaborators as a result of gamma-ray absorption via photon-photon pair production on He II Lyman recombination continuum and lines within the broad-line region.

The Aula Magna at La Sapienza, Rome

It was also made clear that all models we have for description of the high energy emission around pulsars are, more or less, wrong. Fermi has told us for certain that the emission is from high altitudes in the outer magnetosphere; Fermi has killed the polar cap model and the classical TPC, while the other models are in need of modifications. Continue reading The Fermi symposium 2011: AGNs, pulsars and gamma ray bursts

Goodbye Linköping. Hello Kiruna!

Testing PoGOLite at Linköping airport.

During the last couple of months, a large wooden structure has been puzzling passers-by at Linköping airport. Hanging from the structure is PoGOLite – a X-ray telescope which is specifically designed to determine the polarisation of incoming photons. This capability makes PoGOLite unique.

The systems which allow PoGOLite to be accurately pointed on the sky have been put their paces in Linköping. The tests finish this weekend, paving the way for a move to the Esrange Space Centre near Kiruna where a million cubic metre helium-filled balloon will lift PoGOLite to an altitude of 40 km. The ballon launch is foreseen for late June Continue reading Goodbye Linköping. Hello Kiruna!