Astronomy & Astrophysics Seminar: On the nature of long GRB jets and how they can can be used to study the properties of "true" short GRBs

Abstract:

A major question in the study of GRBs is the composition of their jets. The answer to this question has important implications on the energy dissipation processes that leads to the emission of the high energy photons. It can also provide clues for the type of the compact object that powers the jet. In this talk I will discuss the properties of the jets in long GRBs during their propagation inside the progenitor star. I will show the differences between a hydrodynamic jet and a magnetic jet and how we can distinguish between the two by the different times they break out of the star. The breakout time of the jet leaves a distinctive mark on the duration distribution of the long GRBs, or collapsars. As such, it can be used to better separate the collapsar (long) GRBs from the non-collapsar (short) GRBs, producing more homogeneous samples of non-collapsars which can be used to study the properties of non-collapsars. The conclusions derived from the new samples are somewhat different than those that are obtained from the currently used samples, which are selected according to the traditional method of T90<2 sec.

Seminar Organizer: Prof. Rennan Barkana