Andrea Mignone: Frontiers of high-energy computational astrophysics

Speaker: Andrea Mignone, University of Turin

Full title: Frontiers of high-energy computational astrophysics: bridging gaps between large and small scales

Date: 1 Dec 2020

Abstract: High-energy non-thermal astrophysical environments - such as Active Galactic Nuclei, Pulsar Wind Nebulae and Gamma Ray burst - involve magnetized relativistic flows, whose energy flux can be partly converted, at dissipation sites, into random relativistic motion of particles that lose their energy through a variety of non-thermal processes and give rise to the observed radiation. Understanding of these extreme environments requires a detailed description of the highly nonlinear interactions between plasmas, non-thermal relativistic particles and radiation taking place on a wide range of spatial and temporal scales. This has forced practitioners in the field to take a sectorial approach. On the one hand, models at the large scale can be obtained through relativistic magnetohydrodynamical (RMHD) numerical simulations using a fluid model, albeit neglecting the relativistic particle component. On the other, Particle In Cell (PIC) codes allow a deeper comprehension of kinetic phenomena taking place at much smaller scales. As a consequence, the resulting picture is incomplete and fragmentary. In this talk, I will discuss some of the present and future computational perspectives which intend to bridge this gap. This task requires the coupling between large scale dynamics with a detailed treatment of the microphysics at dissipation sites, an extremely challenging task that only now is becoming feasible thanks to the advancements of high performance computing.