Mon. Not. R. Astron. Soc., 446, 3992-4007 (2015/February-1)
Shock finding on a moving mesh - I. Shock statistics in non-radiative cosmological simulations.
SCHAAL K. and SPRINGEL V.
Abstract (from CDS):
Cosmological shock waves play an important role in hierarchical structure formation by dissipating and thermalizing kinetic energy of gas flows, thereby heating the Universe. Furthermore, identifying shocks in hydrodynamical simulations and measuring their Mach number accurately are critical for calculating the production of non-thermal particle components through diffusive shock acceleration. However, shocks are often significantly broadened in numerical simulations, making it challenging to implement an accurate shock finder. We here introduce a refined methodology for detecting shocks in the moving-mesh code arepo, and show that results for shock statistics can be sensitive to implementation details. We put special emphasis on filtering against spurious shock detections due to tangential discontinuities and contacts. Both of them are omnipresent in cosmological simulations, for example in the form of shear-induced Kelvin-Helmholtz instabilities and cold fronts. As an initial application of our new implementation, we analyse shock statistics in non-radiative cosmological simulations of dark matter and baryons. We find that the bulk of energy dissipation at redshift zero occurs in shocks with Mach numbers around M~2.7. Furthermore, almost 40 percent of the thermalization is contributed by shocks in the warm hot intergalactic medium, whereas ~60 percent occurs in clusters, groups, and smaller haloes. Compared to previous studies, these findings revise the characterization of the most important shocks towards higher Mach numbers and lower density structures. Our results also suggest that regions with densities above and below δb = 100 should be roughly equally important for the energetics of cosmic ray acceleration through large-scale structure shocks.
© 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society (2014)
hydrodynamics - shock waves - methods: numerical - galaxies: clusters: general - large-scale structure of Universe
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