http://arxiv.org/abs/1405.3582
We present a high precision strong lensing mass model of the massive galaxy cluster MACSJ0416.1-2403 using the new Hubble Space Telescope Frontier Fields (HFF) data. With the exquisite and unprecedented depth offered by the 3-band HST/ACS observations, we have discovered 51 new multiply-imaged systems, bringing the total number of systems to 68, for a total of 194 images. This dramatic increase in the number of previously known multiple systems provides critical additional constraints that helps derive the mass distribution in the cluster core below the percent level. In comparison, the earlier published mass model used the CLASH survey data with only 23 multiple systems. Using the LENSTOOL software, we build a high precision mass model that comprises of 2 cluster-scale dark matter halos and 98 galaxy-scale halos to describe the mass distribution of MACSJ0416. Concentrating on the subset of 57 multiply imaged systems used in the optimisation, our best-fit mass model has an average error on the predicted image positions of rms = 0.68″, almost a factor of two improvement compared to the rms = 1.17″ obtained with our pre-HFF mass model (using only 17 multiply imaged systems). The total mass within an aperture of 200 kpc is found to be M = 1.60\pm0.01x1e14 Msun. Finally, we quantify the gain in precision on the magnification of high-redshift galaxies, and find an improvement by a factor of ~2.5x in the statistical error. With the new $Hubble Frontier Fields$, we are entering into the domain of high-precision mass measurement for massive galaxy clusters.
M. Jauzac, B. Clement, M. Limousin, et. al.
Thu, 15 May 14
33/55
Comments: submitted to MNRAS, 8 pages, 2 figures, 2 tables
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