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http://hdl.handle.net/20.500.12386/24595
Title: | ALMA-SZ Detection of a Galaxy Cluster Merger Shock at Half the Age of the Universe | Authors: | Basu, K. Sommer, M. Erler, J. Eckert, D. VAZZA, FRANCO Magnelli, B. Bertoldi, F. TOZZI, Paolo |
Issue Date: | 2016 | Journal: | THE ASTROPHYSICAL JOURNAL LETTERS | Number: | 829 | Issue: | 2 | First Page: | L23 | Abstract: | We present ALMA measurements of a merger shock using the thermal Sunyaev-Zel’dovich (SZ) effect signal, at the location of a radio relic in the famous El Gordo galaxy cluster at z≈ 0.9. Multi-wavelength analysis in combination with the archival Chandra data and a high-resolution radio image provides a consistent picture of the thermal and non-thermal signal variation across the shock front and helps to put robust constraints on the shock Mach number as well as the relic magnetic field. We employ a Bayesian analysis technique for modeling the SZ and X-ray data self-consistently, illustrating respective parameter degeneracies. Combined results indicate a shock with Mach number { M }={2.4}<SUB>-0.6</SUB><SUP>+1.3</SUP>, which in turn suggests a high value of the magnetic field (of the order of 4-10 μ {{G}}) to account for the observed relic width at 2 GHz. At roughly half the current age of the universe, this is the highest-redshift direct detection of a cluster shock to date, and one of the first instances of an ALMA-SZ observation in a galaxy cluster. It shows the tremendous potential for future ALMA-SZ observations to detect merger shocks and other cluster substructures out to the highest redshifts. | URI: | http://hdl.handle.net/20.500.12386/24595 | URL: | https://iopscience.iop.org/article/10.3847/2041-8205/829/2/L23 | ISSN: | 2041-8205 | DOI: | 10.3847/2041-8205/829/2/L23 | Bibcode ADS: | 2016ApJ...829L..23B | Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista |
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Basu_2016_ApJL_829_L23.pdf | PDF editoriale | 1.01 MB | Adobe PDF | View/Open |
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