- 제목
- [9/18] Particle Acceleration at Weak shocks in High-beta Intracluster Medium
- 작성일
- 2020.09.15
- 작성자
- 신용광
- 게시글 내용
-
Title: Particle Acceleration at Weak shocks in High-beta Intracluster Medium
Date & Time: Friday, September 18th, 2020, 11:00 AM
Location: Online
( https://zoom.us/j/6210767044?pwd=SkRuRzZtbjcwQkszS2g4QThiWVl3dz09 , It will open at 10:30 AM)
Language: English
Speaker: Prof. Hyesung Kang (Pusan National University)
Abstract
Weak shocks with low sonic Mach numbers are induced by mergers and/or supersonic flow motions in the hot tenuous intracluster medium (ICM). High energy cosmic ray (CR) protons are expected to be accelerated at quasi-parallel shocks via diffusive shock acceleration (DSA), while CR electrons are expected to be accelerated preferentially at quasi-perpendicular shocks. The key element in determining the DSA efficiency is the so-called injection process, which energizes thermal particles to suprathermal energies sufficient to diffuse across the shock transition layer. Reflection of incoming particles and ensuing self-excitation of MHD/plasma waves play important roles in particle injection to DSA. Using particle-in-cell (PIC) simulations, we study the injection and early acceleration of protons and electrons at weak shocks in high beta plasma. We find that the proton (electron) injection at quasi-parallel (quasi-perpendicular) shocks is effective only for supercritical shocks with the sonic Mach number greater than about 2.3. Further investigation is necessary to examine if subcritical shocks can re-accelerate pre-existing populations of protons and electrons in the ICM.
- 발표자
- 강혜성