A measurement of the kinetic sunyaev-zel'dovich signal toward MACS J0717.5+3745

J. Sayers, T. Mroczkowski, M. Zemcov, P. M. Korngut, J. Bock, E. Bulbul, N. G. Czakon, E. Egami, S. R. Golwala, P. M. Koch, K. Y. Lin, A. Mantz, S. M. Molnar, L. Moustakas, E. Pierpaoli, T. D. Rawle, E. D. Reese, M. Rex, J. A. Shitanishi, S. SiegelK. Umetsu

Research output: Contribution to journalArticlepeer-review

69 Scopus citations


We report our analysis of MACS J0717.5+3745 using 140 and 268 GHz Bolocam data collected at the Caltech Submillimeter Observatory. We detect extended Sunyaev-Zel'dovich (SZ) effect signal at high significance in both Bolocam bands, and we employ Herschel-SPIRE observations to subtract the signal from dusty background galaxies in the 268 GHz data. We constrain the two-band SZ surface brightness toward two of the sub-clusters of MACS J0717.5+3745: the main sub-cluster (named C), and a sub-cluster identified in spectroscopic optical data to have a line-of-sight velocity of +3200 km s-1 (named B). We determine the surface brightness in two separate ways: via fits of parametric models and via direct integration of the images. For both sub-clusters, we find consistent surface brightnesses from both analysis methods. We constrain spectral templates consisting of relativistically corrected thermal and kinetic SZ signals, using a jointly-derived electron temperature from Chandra and XMM-Newton under the assumption that each sub-cluster is isothermal. The data show no evidence for a kinetic SZ signal toward sub-cluster C, but they do indicate a significant kinetic SZ signal toward sub-cluster B. The model-derived surface brightnesses for sub-cluster B yield a best-fit, line-of-sight velocity of vz = +3450 ± 900 km s-1, with (1-Prob[v z ≥ 0]) = 1.3 × 10-5 (4.2σ away from 0 for a Gaussian distribution). The directly integrated sub-cluster B SZ surface brightnesses provide a best-fit vz = +2550 ± 1050 km s -1, with (1-Prob[vz ≥ 0]) = 2.2 × 10-3 (2.9σ).

Original languageEnglish (US)
Article number52
JournalAstrophysical Journal
Issue number1
StatePublished - Nov 20 2013


  • galaxies: clusters: intracluster medium

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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