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Published August 31, 2012 | Published
Journal Article Open

CLASH: Precise new constraints on the mass profile of the galaxy cluster A2261

Abstract

We precisely constrain the inner mass profile of A2261 (z = 0.225) for the first time and determine that this cluster is not "overconcentrated" as found previously, implying a formation time in agreement with ΛCDM expectations. These results are based on multiple strong-lensing analyses of new 16-band Hubble Space Telescope imaging obtained as part of the Cluster Lensing and Supernova survey with Hubble. Combining this with revised weaklensing analyses of Subaru wide-field imaging with five-band Subaru + KPNO photometry, we place tight new constraints on the halo virial mass Mvir = (2.2 ± 0.2) × 1015 M h−1 70 (within rvir ≈ 3 Mpc h−1 70 ) and concentration cvir = 6.2 ± 0.3 when assuming a spherical halo. This agrees broadly with average c(M, z) predictions from recent ΛCDM simulations, which span 58. Our most significant systematic uncertainty is halo elongation along the line of sight (LOS). To estimate this, we also derive a mass profile based on archival Chandra X-ray observations and find it to be ∼35% lower than our lensing-derived profile at r2500 ∼ 600 kpc. Agreement can be achieved by a halo elongated with a ∼2:1 axis ratio along our LOS. For this elongated halo model, we find Mvir = (1.7 ± 0.2) × 1015 M h−1 70 and cvir = 4.6 ± 0.2, placing rough lower limits on these values. The need for halo elongation can be partially obviated by non-thermal pressure support and, perhaps entirely, by systematic errors in the X-ray mass measurements. We estimate the effect of background structures based on MMT/Hectospec spectroscopic redshifts and find that these tend to lower Mvir further by ∼7% and increase cvir by ∼5%. Ke

Additional Information

© 2012. The American Astronomical Society. Published 2012 August 31. We thank Nobuhiro Okabe for providing his weak-lensing shape measurement catalog for comparison with this work. We also thank Nobuhiro, Mark Voit, Jack Sayers, and Nicole Czakon for useful discussions. Portions of this collaborative effort were carried out at the Keck Institute for Space Studies, who we thank for their hospitality. We thank Perry Berlind and Mike Calkins for efficient operation of the Hectospec, and we thank Susan Tokarz for running the Hectospec data reduction pipeline. We also thank the referee for excellent detailed comments that significantly improved the manuscript. The CLASH Multi-Cycle Treasury Program is based on observations made with the NASA/ESA Hubble Space Telescope. The Space Telescope Science Institute is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. ACS was developed under NASA Contract NAS 5-32864. This research is supported in part by NASA Grant HSTGO-12065.01-A, National Science Council of Taiwan Grant NSC100-2112-M-001-008-MY3, the Israel Science Foundation, the German Science Foundation (Transregio TR 33), Spanish MICINN Grant YA2010-22111-C03-00, funding from the Junta de Andalucía Proyecto de Excelencia NBL2003, INAF Contracts ASI-INAF I/009/10/0, ASI-INAF I/023/05/0, ASI-INAF I/088/06/0, PRIN INAF 2009, and PRIN INAF 2010, NSF CAREER Grant AST-0847157, the UK's STFC, the Royal Society, and the Wolfson Foundation. K.U. acknowledges support from the Academia Sinica Career Development Award. A.Z. is supported by contract research Internationale Spitzenforschung II-1 of the Baden-Wurttemberg Stiftung. M.J.G., K.J.R., A.D., and M.J.K. acknowledge partial support from the Smithsonian Institution. K.J.R. was funded in part by a Cottrell College Science Award from the Research Corporation. A.D. gratefully acknowledges partial support from the INFN Grant PD51 and the PRIN-MIUR-2008 Grant 2008NR3EBK_003 "Matter-antimatter asymmetry, dark matter and dark energy in the LHC era." L.I. acknowledges support from a Conicyt FONDAP/BASAL grant. P.R. and S.S. acknowledge support from the DFG cluster of excellence Origin and Structure of the Universe program. Facilities: HST (ACS, WFC3), Subaru (Suprime-Cam), Mayall, CXO (ACIS), MMT (Hectospec)

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August 19, 2023
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