The discovery in 2000 of X-ray emission by Chandra from the large (~100 kpc-Mpc) jets of powerful quasars came as a surprise. As a response a model was proposed that explained the X-rays as inverse Compton scattering off the cosmic microwave background (IC/CMB). This requires the large scale jet to be substantially relativistic (Lorentz factor of the flow ~10-20) and to carry a power comparable to or higher than the Eddington luminosity if the system. This model became the de-facto paradigm of the field although a fraction of the astrophysics community kept raising concerns about it. Back in 2006 we proposed a diagnostic for this model that required long Gamma-ray observations. With the arrival of the Gamma-ray telescope Fermi the diagnostic became feasible and in 2014 and 2015 we presented the first two cases of falsifying the IC/CMB model. I will discuss these considerations and what remains to be done and understood to obtain a more realistic understanding of these extreme plasma flows.

Μετά το τέλος της ομιλίας, θα ακολουθήσει συζήτηση με ενδιαφερόμενους φοιτητές, σχετικά με τις διδακτορικές σπουδές στις Η.Π.Α.