Journal Article

Numerical overcooling in shocks

Peter Creasey, Tom Theuns, Richard G. Bower and Cedric G. Lacey

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 415, issue 4, pages 3706-3720
Published in print August 2011 | ISSN: 0035-8711
Published online August 2011 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2011.19001.x
Numerical overcooling in shocks

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We present a study of cooling in radiative shocks simulated with smoothed particle hydrodynamics and adaptive mesh refinement codes. We obtain a similarity solution for a shock-tube problem in the presence of radiative cooling, and test how well the solution is reproduced in gadget and flash. Shock broadening governed by the details of the numerical scheme (artificial viscosity or Riemann solvers) leads to potentially significant overcooling in both codes. We interpret our findings in terms of a resolution criterion, and apply it to realistic simulations of cosmological accretion shocks on to galaxy haloes, cold accretion and thermal feedback from supernovae or active galactic nuclei (AGN). To avoid numerical overcooling of accretion shocks on to haloes that should develop a hot corona a particle or cell mass resolution of 106 M is required, which is within reach of current state-of-the-art simulations. At this mass resolution, thermal feedback in the interstellar medium of a galaxy requires temperatures of supernova- or AGN-driven bubbles to be in excess of 107 K at densities of nH= 1.0 cm−3, in order to avoid spurious suppression of the feedback by numerical overcooling.

Keywords: hydrodynamics; shock waves; methods: numerical; galaxies: formation; galaxies: ISM

Journal Article.  12381 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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