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Rhapsody-G simulations: galaxy clusters as baryonic closed boxes and the covariance between hot gas and galaxies

Wu, Hao-Yi ; Evrard, August E. ; Hahn, Oliver ; Martizzi, Davide ; Teyssier, Romain ; Wechsler, Risa H.

In: Monthly Notices of the Royal Astronomical Society, 2015, vol. 452, no. 2, p. 1982-1991

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    Title
    • Rhapsody-G simulations: galaxy clusters as baryonic closed boxes and the covariance between hot gas and galaxies
    Author
    • Wu, Hao-Yi. Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA
    • Evrard, August E.. Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA
    • Hahn, Oliver. Department of Physics, ETH Zurich, CH-8093 Zürich, Switzerland
    • Martizzi, Davide. Department of Astronomy, University of California, Berkeley, CA 94720-3411, USA
    • Teyssier, Romain. Institute for Computational Science, University of Zurich, CH-8057 Zürich, Switzerland
    • Wechsler, Risa H.. KIPAC, Physics Department, Stanford University, Stanford, CA 94305, USA
    Document Type
    • Postprint
    Language
    • English
    Published in
    • Monthly Notices of the Royal Astronomical Society, 2015, vol. 452, no. 2, p. 1982-1991. Oxford University Press
    Other Version
    OAI-PMH Identifier
    • oai:doc.rero.ch:301380
    Summary
    Within a sufficiently large cosmic volume, conservation of baryons implies a simple ‘closed box' view in which the sum of the baryonic components must equal a constant fraction of the total enclosed mass. We present evidence from Rhapsody-G hydrodynamic simulations of massive galaxy clusters that the closed-box expectation may hold to a surprising degree within the interior, non-linear regions of haloes. At a fixed halo mass, we find a significant anti-correlation between hot gas mass fraction and galaxy mass fraction (cold gas+stars), with a rank correlation coefficient of −0.69 within R500c. Because of this anti-correlation, the total baryon mass serves as a low-scatter proxy for total cluster mass. The fractional scatter of total baryon fraction scales approximately as 0.02(Δc/100)0.6, while the scatter of either gas mass or stellar mass is larger in magnitude and declines more slowly with increasing radius. We discuss potential observational tests using cluster samples selected by optical and hot gas properties; the simulations suggest that joint selection on stellar and hot gas has potential to achieve 5 per cent scatter in total halo mass