Turbulence-induced magnetic fields in shock precursors
arXiv:1602.03135 · doi:10.1093/mnras/stw340
Abstract
Galactic cosmic rays are believed to be mostly accelerated at supernova shocks. However, the interstellar magnetic field is too weak to efficiently accelerate galactic cosmic rays up to the highest energies, i.e. eV. A stronger magnetic field in the pre-shock region could provide the efficiency required. Bell's cosmic-ray nonresonant streaming instability has been claimed to be responsible for the amplification of precursor magnetic fields. However, an alternative mechanism has been proposed in which the cosmic-ray pressure gradient forms the shock precursor and drives turbulence, amplifying the magnetic field via the small-scale dynamo. A key ingredient for the mechanism to operate are the inhomogeneities present in the interstellar medium (ISM). These inhomogeneities are the consequence of turbulence. In this work we explore the magnetic field amplification in different ISM conditions through 3D MHD numerical simulations.
17 pages, 19 figures; accepted for publication in MNRAS
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- Shock acceleration with oblique and turbulent magnetic fields
- Discovery of Kolmogorov-like Magnetic Energy Spectrum in Tycho's Supernova Remnant by Two-point Correlations of Synchrotron Intensity
- On the growth of the thermally modified non-resonant streaming instability
- A hadronic emission model for black hole-disc impacts in the blazar OJ 287
- Lagrangian statistics of a shock-driven turbulent dynamo in decaying turbulence
- Diffusive Shock Acceleration and Turbulent Reconnection
- Quasi-perpendicular shock acceleration and TDE radio flares
- The high-energy emission from HD~93129A near periastron
- On the Potential of Faraday Tomography to Identify Shock Structures in Supernova Remnants
- Time-dependent treatment of cosmic-ray spectral steepening due to turbulence driving
- Acoustic instability at shock-wave precursors