TY  - JOUR
A1  - Thomas, Timon
A1  - Pfrommer, Christoph
A1  - Pakmor, Rüdiger
T1  - A finite volume method for two-moment cosmic ray hydrodynamics on a moving mesh
T2  - Monthly notices of the Royal Astronomical Society
N2  - We present a new numerical algorithm to solve the recently derived equations of two-moment cosmic ray hydrodynamics (CRHD). The algorithm is implemented as a module in the moving mesh AREPO code. Therein, the anisotropic transport of cosmic rays (CRs) along magnetic field lines is discretized using a path-conservative finite volume method on the unstructured time-dependent Voronoi mesh of AREPO. The interaction of CRs and gyroresonant Alfven waves is described by short time-scale source terms in the CRHD equations. We employ a custom-made semi-implicit adaptive time stepping source term integrator to accurately integrate this interaction on the small light-crossing time of the anisotropic transport step. Both the transport and the source term integration step are separated from the evolution of the magnetohydrodynamical equations using an operator split approach. The new algorithm is tested with a variety of test problems, including shock tubes, a perpendicular magnetized discontinuity, the hydrodynamic response to a CR overpressure, CR acceleration of a warm cloud, and a CR blast wave, which demonstrate that the coupling between CR and magnetohydrodynamics is robust and accurate. We demonstrate the numerical convergence of the presented scheme using new linear and non-linear analytic solutions.
KW  - hydrodynamics
KW  - MHD
KW  - methods: numerical
KW  - cosmic rays
Y1  - 2021
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/62822
SN  - 0035-8711
SN  - 1365-2966
VL  - 503
IS  - 2
SP  - 2242
EP  - 2264
PB  - Oxford University Press
CY  - Oxford
ER  -