Lecturer: Dr. Asaf Pe'er Affiliation: University College Cork Abstract: Since the launch of Fermi in 2008, a prime focus had been given to understanding the physical origin of the prompt emission from gamma-ray bursts (GRBs), which holds the key to understanding of their nature. While the problem is still far from being solved, in recent years we are witnessing a "paradigm shift", as the existence of a thermal component (on top the non-thermal emission) becomes evident. I will describe some latest results and the recent theoretical breakthroughs in understanding how the naively expected "Planck" spectrum can be broadened and resemble the observed spectra. I will discuss some novel effects and theoretical ideas relevant for the study of many astronomical objects. As a few examples, I will show how emission from the photosphere can be observed to have high degree of polarization; how it can be used to infer the jet magnetization; and more. Additional details of the upcoming Astrophysics' seminars can be found on the following link. ‏האירוע הזה כולל שיחת וידאו ב-Google Hangouts. הצטרף: https://hangouts.google.com/hangouts/_/mail.huji.ac.il/tba-dr-asaf-pe?hceid=bWFpbC5odWppLmFjLmlsX2c0czhydDlpcmhwZzRvdGNybWIzZGFqcjdvQGdyb3VwLmNhbGVuZGFyLmdvb2dsZS5jb20.6rvrm87pi3pgggod7eqhv9niss&hs=121