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| DOI | 10.1093/MNRAS/STAC319 | ||||
| Año | 2022 | ||||
| Tipo | artículo de investigación |
Citas Totales
Autores Afiliación Chile
Instituciones Chile
% Participación
Internacional
Autores
Afiliación Extranjera
Instituciones
Extranjeras
Owing to the complexity of turbulent magnetic fields, modelling the diffusion of cosmic rays is challenging. Based on the current understanding of anisotropic magnetohydrodynamic (MHD) turbulence, we use test particles to examine the cosmic rays' superdiffusion in the direction perpendicular to the mean magnetic field. By changing Alfven Mach number M-A and sonic Mach number M-S of compressible MHD simulations, our study covers a wide range of astrophysical conditions including subsonic warm gas phase and supersonic cold molecular gas. We show that freely streaming cosmic rays' perpendicular displacement increases as 3/2 to the power of the time travelled along local magnetic field lines. This power-law index changes to 3/4 if the parallel propagation is diffusive. We find that the cosmic rays' parallel mean free path decreases in a power-law relation of M-A(-2) in supersonic turbulence. We investigate the energy fraction of slow, fast, and Alfvenic modes and confirm the dominance of Alfvenic modes in the perpendicular superdiffusion. In particular, the energy fraction of fast mode, which is the main agent for pitch-angle scattering, increases with M-A, but is insensitive to M-S >= 2. Accordingly, our results suggest that the suppressed diffusion in supersonic molecular clouds arises primarily due to the variations of M-A instead of M-S.
| Ord. | Autor | Género | Institución - País |
|---|---|---|---|
| 1 | Hu, Yue | - |
UNIV WISCONSIN - Estados Unidos
University of Wisconsin-Madison - Estados Unidos UW-Madison College of Engineering - Estados Unidos |
| 2 | Lazarian, A. | Hombre |
UNIV WISCONSIN - Estados Unidos
Universidad Bernardo O'Higgins - Chile University of Wisconsin-Madison - Estados Unidos |
| 3 | Xu, Siyao | - |
Inst Adv Study - Estados Unidos
Institute for Advanced Studies - Estados Unidos Institute for Advanced Study - Estados Unidos |
| Fuente |
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| National Science Foundation |
| NSF |
| NASA |
| National Aeronautics and Space Administration |
| NASA - Space Telescope Science Institute |
| NASA ATP |
| NASA TCAN |
| Agradecimiento |
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| YH acknowledges the support of the NASA TCAN 144AAG1967. AL acknowledges the support of the NSF grant AST 1715754 and NASA ATP AAH7546. SX acknowledges the support for this work provided by NASA through the NASA Hubble Fellowship grant #HST-HF2-51473.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5- 26555. |
| YH acknowledges the support of the NASA TCAN 144AAG1967 The support of the NSF grant AST 1715754 |