Cosmic-ray Particle Acceleration by Galactic Microquasar Jets
speaker: Haruka Sakemi
Abstract:
Cosmic-ray particles occupy a large portion of the energy distribution of our galaxy. Most of the particles below 10^15 eV are considered to be accelerated by diffusive shock acceleration (DSA) at galactic supernova remnants (SNRs). However, the origin of the particles in the energy range of 10^15-10^18 eV has not been explained yet. Recently, galactic microquasar jets are focused on as a candidate accelerator in this energy range, and theoretical and observational studies get active to investigate the dominant mechanism of acceleration and the energetics.We focus on the most famous microquasar, SS433. It is located at the center of a large radio nebula W50, and the nebula and the jets ejected from SS433 are considered to be interacting. Along the eastern jet axis, there are two candidate regions in which cosmic-ray particle acceleration may occur. One is the region at which the jet broke through W50, and recent HAWC observation identified a TeV gamma-ray emission from the point. The other is the jet terminal region in which the terminal shock should be formed and bright at radio and X-ray. We investigated the jet terminal region using the observational data with the Australia Telescope Compact Array (ATCA) and the NSF’s Karl G. Jansky Very Large Array (VLA) at a few GHz. We revealed the features of magnetic fields and motion of this region, and finally estimated the maximum energy which can be reached by the particle acceleration at the jet terminal shock. We also estimated the total energy of cosmic-ray particles accelerated by the SS433/W50 system based on the observations of HI gas and the gamma-ray emission. In this presentation, I will review my research and future plan.