04/19/2023
By Lynne Schaufenbil
Abstract:
Despite its very close proximity to Earth, there are still many unsolved puzzles about the Sun. One such example of significant recent interest relates to the GeV-TeV gamma-ray emission from the solar disk. This energy range emission is caused by the interaction of galactic cosmic rays with the solar atmosphere. The main goal of our work is to find a theoretical model that explains the mechanisms behind gamma-ray emission. Indeed, the only existing theoretical model can not fully explain the observed spectrum by Fermi Gamma-ray Space Telescope, which is significantly brighter and harder than predicted. Moreover, the theory fails to predict peculiar features of the observed gamma-ray flux, such as its anti-correlation with the solar cycle phases. Here we investigate the trajectories of GeV-TeV galactic cosmic rays as they move within the magnetic field near the solar surface. We performed numerical simulations through the PLUTO code for astrophysical fluid dynamics in which test-particle protons injected at different altitudes evolve on a static magnetic-arcade field model with a turbulent component. Some protons are trapped as they gyrate around the magnetic arcades, some fall toward the Sun’s surface, and others escape the magnetic arcade region away from the Sun. We focus on the latter, as these particles escaping from the Sun can produce gamma rays that are observed at Earth.
Biosketch: I am a new post-doc at the University of Arizona, under the supervision of Federico Fraschetti, currently investigating the transport of GeV-TeV galactic cosmic rays and modeling the gamma-ray emission observed by Fermi Gamma-ray Space Telescope. Before moving to Arizona, I received my Ph.D. from the University of Turin (Italy) under the supervision of Andrea Mignone. I am fascinated by several aspects of theoretical and computational high-energy astrophysics. In particular, I am interested in studying particle acceleration in astrophysical plasmas to understand the origin and acceleration of cosmic rays, aiming to model the spectrum observed from astrophysical sources.
If you are interested in attending, please contact Lynne_Schaufenbil@uml.edu for the Zoom link.