Work

Spectral curvature and breaks from Fermi acceleration at oblique shocks

Year: 2025

Type: article

Abstract: ABSTRACT A major attraction of diffusive shock acceleration is the prediction of power-law spectra for energetic particle distributions. However, this property is not fundamental to the theory. We demonstrate that for planar shocks with an oblique magnetic field the generation of power-law spectra critically requires the particles’ scattering rate to be both directly proportional to their gyro radius (Bohm scaling) and spatially uniform. Non-Bohm scaling results in curved spectra at oblique shocks, while abrupt changes in the spatial profile of the scattering upstream introduces spectral breaks. Using the publicly available code sapphire++, we numerically explore the magnitude of these effects, which are particularly pronounced at fast shocks, as expected in active galactic nuclei and microquasar jets, or young supernova remnants.

Source: Monthly Notices of the Royal Astronomical Society Letters

DOI: 10.1093/mnrasl/slaf113

Authors: Asma Shirin T, Brian Reville, Nils W Schween, Florian Schulze, John G Kirk

Institutions: Indian Institute of Science Education and Research, Tirupati, Max Planck Institute for Nuclear Physics

Language: English

Topic: Astrophysics and Cosmic Phenomena

Subfield: Nuclear and High Energy Physics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $1,451

Funder: Max Planck Institute for Nuclear Physics