Μάρκος Γεωργανόπουλος, Assoc. Prof.
University of Maryland, Baltimore County
University of Maryland, Baltimore County
ο Τομέας Αστροφυσικής, Αστρονομίας και Μηχανικής σας προσκαλεί στο
σεμινάριο της ΠΑΡΑΣΚΕΥΗΣ 24/6/2016 και ώρα 12:00, στο Αστεροσκοπείο.
Περίληψη:
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.
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.
