CLASH: Precise New Constraints on the Mass Profile of the Galaxy Cluster A2261
Donahue, Megan; Broadhurst, Tom; Maoz, Dan; Moustakas, John; Jha, Saurabh; Zheng, Wei; Riess, Adam; Diaferio, Antonaldo; Zitrin, Adi; Coe, Dan; Umetsu, Keiichi; Bradley, Larry; Ogaz, Sara; Anguita, Timo; Medezinski, Elinor; Postman, Marc; Carrasco, Mauricio; Geller, Margaret J.; Rines, Kenneth J.; Kurtz, Michael J.; Koekemoer, Anton; Nonino, Mario; Molino, Alberto; Mahdavi, Andisheh; Lemze, Doron; Infante, Leopoldo; Melchior, Peter; Host, Ole; Ford, Holland; Grillo, Claudio; Rosati, Piero; Jiménez-Teja, Yolanda; Ascaso, Begoña; Lahav, Ofer; Bartelmann, Matthias; Benítez, Narciso; Bouwens, Rychard; Graur, Or; Graves, Genevieve; Jouvel, Stephanie; Kelson, Daniel; Moustakas, Leonidas; Meneghetti, Massimo; Merten, Julian; Rodney, Steve; Seitz, Stella
United States, Taiwan, Germany, Chile, Italy, Spain, United Kingdom, Netherlands, Israel
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 r vir ≈ 3 Mpc h -1 70) and concentration c vir = 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 <~ langcrang <~ 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 r 2500 ~ 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 M vir = (1.7 ± 0.2) × 1015 M ⊙ h -1 70 and c vir = 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 M vir further by ~7% and increase c vir by ~5%.