The observations of the first gravitational wave by the Laser Interferometer Gravitational-Wave Observatory (LIGO) captured the attention of the world this February, confirming the existence of gravitational waves as well as further confirming Einstein’s theory of general relativity.
On June 3rd 2013 at 15:49 UT NASA’s Swift satellite detected an intense flash of γ -rays known as a short γ-ray burst. Follow-up observations by the Hubble Space Telescope revealed infrared emission that was present 9 days after the burst, but had faded away after 30 days.
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.
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.
Last week, Jan Conrad and I spent a couple of days in Dublin, Ireland, invited by Felix Aharonian and his colleagues at DIAS. We had interesting dicussions around many topics, the most interesting being the possibility to obtain a lower energy threshold for gamma-rays at imaging air Cherenkov telescopes, for instance by using large mirrors at high altitude.