All posts by Felix Ryde

Fermi/Swift GRB Symposium 2012: Polarisation and thermal emission in GRBs

The Fermi/Swift gamma-ray burst Symposium 2012 was held in Munich 7-11 May 2012. Recent results on the prompt and afterglow emissions in gamma-ray burst were discussed at the Fermi/Swift gamma-ray burst Symposium 2012 which was held in Munich 7-11 May 2012. Among the most important issues presented was the recent gamma-polarisation measurement with IKAROS-GAP. Significant degrees of polarisation in several bursts have now been detected. In particular, the change in polarisation angle was significantly detected. It was speculated that this is due to variation in emission patches in very narrowly collimated … Continue Reading ››

First image from the Onsala LOFAR station

The Europe-wide, international LOFAR Telescope (Low Frequency Array) is the world’s largest radio telescope and observes radio waves with low frequencies.
LOFAR will map these radio signals and thereby see billions of light years out into space, into the era when the first stars formed, only a few hundred million years after the Big Bang. However, it will also investigate the environments of black holes, find extreme galaxies and pulsars, for planets around other stars and even investigate the nearest star, our Sun.

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.

Dissipative photospheres in gamma-ray bursts

One of the many research topics at OKC is the study of gamma-ray bursts (GRBs). Several aspects of them are studied, such as the gamma-ray and X-ray emission, the afterglow emission, and the interaction between the bursts and the circumburst medium.

In a recent paper based on observations with the Fermi Gamma-ray Space Telescope it is argued that the main emission during the first few minutes of GRBs is dominated by the jet photosphere and that there is significant amount of energy dissipation close to the photosphere. This result is significant for our understanding of physics of GRB jets.