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Mapping the kinetic Sunyaev-Zel'dovich effect toward MACS J0717.5+3745 with NIKA

Adam, R., Bartalucci, I., Pratt, G. W., Ade, Peter ORCID:, André, P., Arnaud, M., Beelen, A., Benoît, A., Bideaud, A., Billot, N., Bourdin, H., Bourrion, O., Calvo, M., Catalano, A., Coiffard, G., Comis, B., D'Addabbo, A., De Petris, M., Démoclès, J., Désert, F.-X., Doyle, Simon ORCID:, Egami, E., Ferrari, C., Goupy, J., Kramer, C., Lagache, G., Leclercq, S., Macías-Pérez, J.-F., Maurogordato, S., Mauskopf, Philip ORCID:, Mayet, F., Monfardini, A., Mroczkowski, T., Pajot, F., Pascale, Enzo ORCID:, Perotto, L., Pisano, Giampaolo ORCID:, Pointecouteau, E., Ponthieu, N., Revéret, V., Ritacco, A., Rodriguez, L., Romero, C., Ruppin, F., Schuster, K., Sievers, A., Triqueneaux, S., Tucker, Carole ORCID:, Zemcov, M. and Zylka, R. 2017. Mapping the kinetic Sunyaev-Zel'dovich effect toward MACS J0717.5+3745 with NIKA. Astronomy and Astrophysics 598 , A115. 10.1051/0004-6361/201629182

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Measurement of the gas velocity distribution in galaxy clusters provides insight into the physics of mergers, through which large scale structures form in the Universe. Velocity estimates within the intracluster medium (ICM) can be obtained via the Sunyaev-Zel’dovich (SZ) effect, but its observation is challenging both in term of sensitivity requirement and control of systematic effects, including the removal of contaminants. In this paper we report resolved observations, at 150 and 260 GHz, of the SZ effect toward the triple merger MACS J0717.5+3745 (z = 0.55), using data obtained with the NIKA camera at the IRAM 30 m telescope. Assuming that theSZ signal is the sum of a thermal (tSZ) and a kinetic (kSZ) component and by combining the two NIKA bands, we extract for the first time a resolved map of the kSZ signal in a cluster. The kSZ signal is dominated by a dipolar structure that peaks at −5.1 and + 3.4σ, corresponding to two subclusters moving respectively away and toward us and coincident with the cold dense X-ray core and a hot region undergoing a major merging event. We model the gas electron density and line-of-sight velocity of MACS J0717.5+3745 as four subclusters. Combining NIKA data with X-ray observations from XMM-Newton and Chandra, we fit this model to constrain the gas line-of-sight velocity of each component, and we also derive, for the first time, a velocity map from kSZ data (i.e. that is model-dependent). Our results are consistent with previous constraints on the merger velocities, and thanks to the high angular resolution of our data, we are able to resolve the structure of the gas velocity. Finally, we investigate possible contamination and systematic effects with a special care given to radio and submillimeter galaxies. Among the sources that we detect with NIKA, we find one which is likely to be a high redshift lensed submillimeter galaxy.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Physics and Astronomy
Additional Information: PDF uploaded in accordance with publisher's policies at (accessed 17.3.17).
Publisher: EDP Sciences
ISSN: 0004-6361
Date of First Compliant Deposit: 16 March 2017
Date of Acceptance: 8 December 2016
Last Modified: 23 Jul 2024 19:25

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