PIRSA:23100116

Unveiling a Novel Plasma Instability: Impacts on Galaxy Formation and Electron Acceleration at Astrophysical Shocks

Shalaby, M. (2023). Unveiling a Novel Plasma Instability: Impacts on Galaxy Formation and Electron Acceleration at Astrophysical Shocks. Perimeter Institute. https://pirsa.org/23100116

Shalaby, Mohamad. Unveiling a Novel Plasma Instability: Impacts on Galaxy Formation and Electron Acceleration at Astrophysical Shocks. Perimeter Institute, Oct. 26, 2023, https://pirsa.org/23100116 

          @misc{ pirsa_PIRSA:23100116,
            doi = {10.48660/23100116},
            url = {https://pirsa.org/23100116},
            author = {Shalaby, Mohamad},
            keywords = {Strong Gravity},
            language = {en},
            title = {Unveiling a Novel Plasma Instability: Impacts on Galaxy Formation and Electron Acceleration at Astrophysical Shocks},
            publisher = {Perimeter Institute},
            year = {2023},
            month = {oct},
            note = {PIRSA:23100116 see, \url{https://pirsa.org}}
          }

Mohamad Shalaby

Perimeter Institute for Theoretical Physics

Talk number
PIRSA:23100116
Collection
Talk Type
Subject
Abstract

Cosmic-ray-driven instabilities play a crucial role in particle acceleration at shocks and during the propagation of GeV cosmic rays in galaxies and galaxy clusters within the self-confinement picture of CR transport. These instabilities amplify magnetic fields, which, in turn, scatter cosmic rays and thus self-regulate their transport. This leads to a strong coupling between the collisionless cosmic ray population and the thermal background plasma, implying potentially significant dynamic feedback. In this presentation, I discuss a recent discovery of a new cosmic ray-driven instability, referred to as the intermediate-scale instability, which triggers comoving ion-cyclotron electromagnetic waves at sub-ion skin-depth scales. Its growth rate is notably faster compared to the ion gyro scale (streaming) instability, which is commonly assumed to be the dominant instability in the self-confinement picture. Therefore, this new instability could play a vital role in the transport of cosmic rays in galactic and stellar environments. I then explore the implications of this instability for electron acceleration at non-relativistic shocks. Through Particle-in-cell (PIC) simulations, it is demonstrated that the new instability triggers the dominant mechanism for efficient electron acceleration at parallel electron-ion shocks, addressing a persistent issue with electron injection at these shocks. The PIC simulations also reveal that the common practice of using reduced ion-to-electron mass ratios in shock simulations, which artificially suppresses the intermediate instability, not only hinders electron acceleration but also leads to incorrect electron and ion heating in downstream and shock transition areas.

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Zoom link https://pitp.zoom.us/j/91367222746?pwd=REpEdXE3ZGdLeVQ1bnh0NldIQktWQT09