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Galaxies that shine: radiation-hydrodynamical simulations of disc galaxies

Rosdahl, Joakim ; Schaye, Joop ; Teyssier, Romain ; Agertz, Oscar

In: Monthly Notices of the Royal Astronomical Society, 2015, vol. 451, no. 1, p. 34-58

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    Title
    • Galaxies that shine: radiation-hydrodynamical simulations of disc galaxies
    Author
    • Rosdahl, Joakim. Leiden Observatory, Leiden University, PO Box 9513, NL-2300 RA Leiden, the Netherlands
    • Schaye, Joop. Leiden Observatory, Leiden University, PO Box 9513, NL-2300 RA Leiden, the Netherlands
    • Teyssier, Romain. Institute for Computational Science, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
    • Agertz, Oscar. Department of Physics, University of Surrey, Guildford, GU2 7XH Surrey, UK
    Document Type
    • Postprint
    Language
    • English
    Published in
    • Monthly Notices of the Royal Astronomical Society, 2015, vol. 451, no. 1, p. 34-58. Oxford University Press
    Other Version
    OAI-PMH Identifier
    • oai:doc.rero.ch:301197
    Summary
    Radiation feedback is typically implemented using subgrid recipes in hydrodynamical simulations of galaxies. Very little work has so far been performed using radiation-hydrodynamics (RHD), and there is no consensus on the importance of radiation feedback in galaxy evolution. We present RHD simulations of isolated galaxy discs of different masses with a resolution of 18pc. Besides accounting for supernova feedback, our simulations are the first galaxy-scale simulations to include RHD treatments of photoionization heating and radiation pressure, from both direct optical/UV radiation and multiscattered, re-processed infrared (IR) radiation. Photoheating smooths and thickens the discs and suppresses star formation about as much as the inclusion of (‘thermal dump') supernova feedback does. These effects decrease with galaxy mass and are mainly due to the prevention of the formation of dense clouds, as opposed to their destruction. Radiation pressure, whether from direct or IR radiation, has little effect, but for the IR radiation we show that its impact is limited by our inability to resolve the high optical depths for which multiscattering becomes important. While artificially boosting the IR optical depths does reduce the star formation, it does so by smoothing the gas rather than by generating stronger outflows. We conclude that although higher resolution simulations, and potentially also different supernova implementations, are needed for confirmation, our findings suggest that radiation feedback is more gentle and less effective than is often assumed in subgrid prescriptions