Mapping the kinetic Sunyaev-Zel’dovich effect toward MACS J0717.5+3745 with NIKA
Pratt, G. W.
De Petris, M.
AffiliationUniv Arizona, Steward Observ
Keywordstechniques: high angular resolution
galaxies: clusters: individual: MACS J0717.5+3745
galaxies: clusters: intracluster medium
MetadataShow full item record
PublisherEDP SCIENCES S A
CitationMapping the kinetic Sunyaev-Zel’dovich effect toward MACS J0717.5+3745 with NIKA 2017, 598:A115 Astronomy & Astrophysics
JournalAstronomy & Astrophysics
Rights© ESO, 2017
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at firstname.lastname@example.org.
AbstractMeasurement 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 the SZ 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 + 3.4 sigma, 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.
NoteOpen Access Journal.
VersionFinal published version
SponsorsFoundation Nanoscience Grenoble; LabEx FOCUS [ANR-11-LABX-0013]; ANR [ANR-15-CE31-0017]; European Research Council Advanced Grant ORISTARS under the European Union's Seventh Framework Programme ; ENIGMASS French LabEx; CNES post-doctoral fellowship program; CNES doctoral fellowship program; FOCUS French LabEx doctoral fellowship program; French Agence Nationale de la Recherche [ANR-11-BS56-015]; European Research Council under the European Unions Seventh Framework Programme (FP7)/ERC grant