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Gas clumping in galaxy clusters

Eckert, D. ; Roncarelli, M. ; Ettori, S. ; Molendi, S. ; Vazza, F. ; Gastaldello, F. ; Rossetti, M.

In: Monthly Notices of the Royal Astronomical Society, 2015, vol. 447, no. 3, p. 2198-2208

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    Titre
    • Gas clumping in galaxy clusters
    Auteur
    • Eckert, D.. Astronomical Observatory of the University of Geneva, ch. d'Ecogia 16, CH-1290 Versoix, Switzerland
    • Roncarelli, M.. Dipartimento di Fisica e Astronomia, Universit di Bologna, viale Berti Pichat 6/2, I-40127 Bologna, Italy
    • Ettori, S.. INAF - Osservatorio Astronomico di Bologna, Via Ranzani 1, I-40127 Bologna, Italy
    • Molendi, S.. INAF - IASF-Milano, Via E. Bassini 15, I-20133 Milano, Italy
    • Vazza, F.. INAF - Osservatorio Astronomico di Bologna, Via Ranzani 1, I-40127 Bologna, Italy
    • Gastaldello, F.. INAF - IASF-Milano, Via E. Bassini 15, I-20133 Milano, Italy
    • Rossetti, M.. INAF - IASF-Milano, Via E. Bassini 15, I-20133 Milano, Italy
    Type de document
    • Postprint
    Langue
    • Inglese
    Publié dans
    • Monthly Notices of the Royal Astronomical Society, 2015, vol. 447, no. 3, p. 2198-2208. Oxford University Press
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:292024
    Summary
    The reconstruction of galaxy cluster's gas density profiles is usually performed by assuming spherical symmetry and averaging the observed X-ray emission in circular annuli. In the case of a very inhomogeneous and asymmetric gas distribution, this method has been shown to return biased results in numerical simulations because of the n2 dependence of the X-ray emissivity. We propose a method to recover the true density profiles in the presence of inhomogeneities, based on the derivation of the azimuthal median of the surface brightness in concentric annuli. We demonstrate the performance of this method with numerical simulations, and apply it to a sample of 31 galaxy clusters in the redshift range 0.04-0.2 observed with ROSAT/Position Sensitive Proportional Counter (PSPC). The clumping factors recovered by comparing the mean and the median are mild and show a slight trend of increasing bias with radius. For R