Dr. Asaf Pe’er

University College Cork (Ireland), Bar-Ilan Universtiy (Israel)

GRBs, Cosmic rays and shock waves

Abstract:

The acceleration site of ultra-high energy cosmic rays is still an open question despite extended research.
Over 20 years ago it was proposed that GRBs are good candidates. However, data of GRB prompt emission spectra at the different bands can be used to put strong constraints on the physical conditions of the outflow. I will show that the physical conditions during the GRB prompt emission do not enable the acceleration of particles to ultra-high energies, both within the frames of the synchrotron and the photospheric emission models. I will show that this is the case also for low luminosity (ll) GRBs, such as GRB060218.

(If time permits) I will discuss some recent results on diffusive shock acceleration (DSA) theory. I will describe a new model for particle acceleration in arbitrarily turbulent magnetic field, which bridges the gap between the very weak and strong turbulence regimes. I will discuss the validity and limitations of the “Bohm”-type diffusion model.

Location: 31 Fitzwilliam Place

Upcoming seminars:

https://www.dias.ie/2018/10/23/astronomy-and-astrophysics-seminar-schedule-2019/(opens in a new tab)