1. CLASH: PRECISE NEW CONSTRAINTS ON THE MASS PROFILE OF THE GALAXY CLUSTER A2261.
- Author
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Coe, Dan, Umetsu, Keiichi, Zitrin, Adi, Donahue, Megan, Medezinski, Elinor, Postman, Marc, Carrasco, Mauricio, Anguita, Timo, Geller, Margaret J., Rines, Kenneth J., Diaferio, Antonaldo, Kurtz, Michael J., Bradley, Larry, Koekemoer, Anton, Zheng, Wei, Nonino, Mario, Molino, Alberto, Mahdavi, Andisheh, Lemze, Doron, and Infante, Leopoldo
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GALAXY clusters ,STELLAR mass ,DARK matter ,DARK energy ,ASTRONOMICAL photometry - 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 weak-lensing analyses of Subaru wide-field imaging with five-band Subaru + KPNO photometry, we place tight new constraints on the halo virial mass M
vir = (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 5 ≲ 〈 c〉 ≲ 8. 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%. [ABSTRACT FROM AUTHOR]- Published
- 2012
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