Effect of the non-thermal Sunyaev–Zel’dovich effect on the temperature determination of galaxy clusters

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dc.contributor.author Marchegiani, P.
dc.contributor.author Colafrancesco, S.
dc.date.accessioned 2017-11-16T07:57:19Z
dc.date.available 2017-11-16T07:57:19Z
dc.date.issued 2017-08
dc.identifier.citation Marchegiani, P. and Colafrancesco, S. 2017. Effect of the non-thermal Sunyaev–Zel’dovich effect on the temperature determination of galaxy clusters. Monthly Notices of the Royal Astronomical Society, 469(4), pp.4644-4648. en_ZA
dc.identifier.issn 0035-8711 (Print)
dc.identifier.issn 1365-2966 (Online)
dc.identifier.uri http://hdl.handle.net/10539/23416
dc.description.abstract A recent stacking analysis of Planck HFI data of galaxy clusters led to the derivation of the cluster temperatures using the relativistic corrections to the Sunyaev-Zel'dovich effect (SZE). However, the temperatures of high-temperature clusters, as derived from this analysis, were basically higher than the temperatures derived from X-ray measurements, at a moderate statistical significance of 1.5 sigma. This discrepancy has been attributed by Hurier to calibration issues. In this paper, we discuss an alternative explanation for this discrepancy in terms of a non-thermal SZE astrophysical component. We find that this explanation can work if non-thermal electrons in galaxy clusters have a low minimum momentum (p(1) similar to 0.5-1), and if their pressure is of the order of 20-30 per cent of the thermal gas pressure. Both these conditions are hard to obtain if the non-thermal electrons are mixed with the hot gas in the intracluster medium, but can be possibly obtained if the non-thermal electrons are mainly confined in bubbles with a high amount of non-thermal plasma and a low amount of thermal plasma, or are in giant radio lobes/relics in the outskirts of the clusters. To derive more precise results on the properties of the non-thermal electrons in clusters, and in view of more solid detections of a discrepancy between X-ray- and SZE-derived cluster temperatures that cannot be explained in other ways, it would be necessary to reproduce the full analysis done by Hurier by systematically adding the non-thermal component of the SZE. en_ZA
dc.language.iso en en_ZA
dc.publisher Oxford University Press (OUP) en_ZA
dc.rights This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
dc.subject Galaxies: clusters: general en_ZA
dc.subject Galaxies: clusters: intracluster medium en_ZA
dc.subject Cosmic background radiation en_ZA
dc.subject RADIO-EMISSION en_ZA
dc.subject PLASMA en_ZA
dc.subject SHOCKS en_ZA
dc.subject MATTER en_ZA
dc.title Effect of the non-thermal Sunyaev–Zel’dovich effect on the temperature determination of galaxy clusters en_ZA
dc.type Article en_ZA
dc.journal.volume 469 en_ZA
dc.journal.title Monthly Notices of the Royal Astronomical Society en_ZA
dataset.nrf.grant
dc.description.librarian EM2017 en_ZA
dc.citation.doi 10.1093/mnras/stx1250 en_ZA
dc.citation.epage 4648 en_ZA
dc.citation.issue 4 en_ZA
dc.citation.spage 4644 en_ZA
dc.funder This work is based on research supported by the South African Research Chairs Initiative of the Department of Science and Technology and National Research Foundation of South Africa (no 77948). Paolo Marchegiani (PM) acknowledges support from the Department of Science and Technology/National Research Foundation (DST/NRF) Square Kilometre Array (SKA) post-graduate bursary initiative. en_ZA


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