Details

Autor(en) / Beteiligte

• Power, C.
• Read, J. I.
• Hobbs, A.

Titel

The formation of entropy cores in non-radiative galaxy cluster simulations: smoothed particle hydrodynamics versus adaptive mesh refinement

Ist Teil von

• Monthly notices of the Royal Astronomical Society, 2014-06, Vol.440 (4), p.3243-3256

Ort / Verlag

London: Oxford University Press

Erscheinungsjahr

2014

Quelle

EZB-FREE-00999 freely available EZB journals

Beschreibungen/Notizen

• We simulate cosmological galaxy cluster formation using three different approaches to solving the equations of non-radiative hydrodynamics – classic smoothed particle hydrodynamics (SPH), novel SPH with a higher order dissipation switch (SPHS), and an adaptive mesh refinement (AMR) method. Comparing spherically averaged entropy profiles, we find that SPHS and AMR approaches result in a well-defined entropy core that converges rapidly with increasing mass and force resolution. In contrast, the central entropy profile in the SPH approach is sensitive to the cluster's assembly history and shows poor numerical convergence. We trace this disagreement to the known artificial surface tension in SPH that appears at phase boundaries. Varying systematically numerical dissipation in SPHS, we study the contributions of numerical and physical dissipation to the entropy core and argue that numerical dissipation is required to ensure single-valued fluid quantities in converging flows. However, provided it occurs only at the resolution limit and does not propagate errors to larger scales, its effect is benign – there is no requirement to build ‘sub-grid’ models of unresolved turbulence for galaxy cluster simulations. We conclude that entropy cores in non-radiative galaxy cluster simulations are physical, resulting from entropy generation in shocked gas during cluster assembly.