1107.2649 (A. Zitrin et al.)

CLASH: New Multiple-Images Constraining the Inner Mass Profile of MACS J1206.2-0847    [PDF]

A. Zitrin, P. Rosati, M. Nonino, C. Grillo, M. Postman, D. Coe, S. Seitz, T. Eichner, T. Broadhurst, S. Jouvel, I. Balestra, A. Mercurio, M. Scodeggio, N. Benítez, L. Bradley, H. Ford, O. Host, Y. Jimenez-Teja, A. Koekemoer, W. Zheng, M. Bartelmann, R. Bouwens, O. Czoske, M. Donahue, O. Graur, G. Graves, L. Infante, S. Jha, D. Kelson, O. Lahav, R. Lazkoz, D. Lemze, M. Lombardi, D. Maoz, C. McCully, E. Medezinski, P. Melchior, M. Meneghetti, J. Merten, A. Molino, L. A. Moustakas, S. Ogaz, B. Patel, E. Regoes, A. Riess, S. Rodney, K. Umetsu, A. Van der Wel

We present a strong-lensing analysis of the galaxy cluster MACS J1206.2-0847 ($z$=0.44) using UV, Optical, and IR, HST/ACS/WFC3 data taken as part of the CLASH multi-cycle treasury program, with VLT/VIMOS spectroscopy for some of the multiply-lensed arcs. The CLASH observations, combined with our mass-model, allow us to identify 47 new multiply-lensed images of 12 distant sources. These images, along with the previously known arc, span the redshift range $1\la z\la5.5$, and thus enable us to derive a detailed mass distribution and to accurately constrain, for the first time, the inner mass-profile of this cluster. We find an inner profile slope of $d\log \Sigma/d\log \theta\simeq -0.55\pm 0.1$ (in the range [1\arcsec, 53\arcsec], or $5\la r \la300$ kpc), as commonly found for relaxed and well-concentrated clusters. Using the many systems uncovered here we derive credible critical curves and Einstein radii for different source redshifts. For a source at $z_{s}\simeq2.5$, the critical curve encloses a large area with an effective Einstein radius of $\theta_{E}=28\pm3\arcsec$, and a projected mass of $1.34\pm0.15\times10^{14} M_{\odot}$. From the current understanding of structure formation in concordance cosmology, these values are relatively high for clusters at $z\sim0.5$, so that detailed studies of the inner mass distribution of clusters such as MACS J1206.2-0847 can provide stringent tests of the $\Lambda$CDM paradigm.

View original: http://arxiv.org/abs/1107.2649