English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

A major uncertainty in understanding the transport and feedback ofcosmic-rays (CRs) within and beyond our Galaxy lies in the unknown CRscattering rates, which are primarily determined by wave-particle interactionat microscopic gyro-resonant scales. The source of the waves for the bulk CRpopulation is believed to be self-driven by the CR streaming instability(CRSI), resulting from the streaming of CRs downward a CR pressure gradient.While a balance between driving by the CRSI and wave damping is expected todetermine wave amplitudes and hence the CR scattering rates, the probleminvolves significant scale separation with substantial ambiguities based onquasi-linear theory (QLT). Here we propose a novel "streaming box" framework tostudy the CRSI with an imposed CR pressure gradient, enabling first-principlemeasurement of the CR scattering rates as a function of environmentalparameters. By employing the magnetohydrodynamic-particle-in-cell (MHD-PIC)method with ion-neutral damping, we conduct a series of simulations withdifferent resolutions and CR pressure gradients and precisely measure theresulting CR scattering rates in steady state. The measured rates show scalingsconsistent with QLT, but with a normalization smaller by a factor of severalthan typical estimates based on single-fluid treatment of CRs. Amomentum-by-momentum treatment provides better estimates when integrated overmomentum, but is also subject substantial deviations especially at smallmomentum. Our framework thus opens up the path towards providing comprehensivesubgrid physics for macroscopic studies of CR transport and feedback in broadastrophysical contexts.

Towards First-principle Characterization of Cosmic-ray Transport Coefficients from Multi-scale Kinetic Simulations