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TOPIC: MACS J0416.1-2403

Blobrana

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Posts: 131433

Date: Jul 24 21:08 2014

RE: MACS J0416.1-2403	Permalink

New mass map of a distant galaxy cluster is the most precise yet Astronomers using the NASA/ESA Hubble Space Telescope have mapped the mass within a galaxy cluster more precisely than ever before. Created using observations from Hubble's Frontier Fields observing programme, the map shows the amount and distribution of mass within MCS J0416.12403, a massive galaxy cluster found to be 160 trillion times the mass of the Sun. The detail in this mass map was made possible thanks to the unprecedented depth of data provided by new Hubble observations, and the cosmic phenomenon known as strong gravitational lensing. Read more __________________

Blobrana

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Posts: 131433

Date: May 15 08:07 2014

MACSJ0416.1-2403	Permalink

Title: Hubble Frontier Fields : High Precision Strong Lensing Analysis of the Cluster MACSJ0416.1-2403 using ~200 Multiple Images Author: Mathilde Jauzac, Benjamin Clément, Marceau Limousin, Eric Jullo, Johan Richard, Jean-Paul Kneib, Hakim Atek, Priyamvada Natarajan, Kenda Knowles, Harald Ebeling, Dominique Eckert, Eiichi Egami, Richard Massey, Markus Rexroth 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 HubbleFrontierFields, we are entering into the domain of high-precision mass measurement for massive galaxy clusters. Read more (357kb, PDF) __________________

Blobrana

L

Posts: 131433

Date: Nov 13 17:56 2012

MACS J0416.1-2403	Permalink

Title: CLASH: The enhanced lensing efficiency of the highly elongated merging cluster MACS J0416.1-2403 Authors: A. Zitrin, M. Meneghetti, K. Umetsu, T. Broadhurst, M. Bartelmann, R. Bouwens, L. Bradley, M. Carrasco, D. Coe, H. Ford, D. Kelson, A. M. Koekemoer, E. Medezinski, J. Moustakas, L. A. Moustakas, M. Nonino, M. Postman, P. Rosati, G. Seidel, I. Sendra, X. Shu, J. Vega, W. Zheng We perform a strong-lensing analysis of the merging galaxy cluster MACS J0416.1-2403 (M0416; z=0.42) in recent CLASH/HST observations. We identify 70 new multiple images and candidates of 23 background sources in the range 0.7<z_{phot}<6.14 including two probable high-redshift dropouts, revealing a highly elongated lens with axis ratio ~5:1, and a major axis of ~100\arcsec (z_{s}~2). Compared to other well-studied clusters, M0416 shows an enhanced lensing efficiency. Although the critical area is not particularly large (~0.6 \square\arcmin; z_{s}~2), the number of multiple images, per critical area, is anomalously high. We calculate that the observed elongation boosts the number of multiple images, per critical area, by a factor of ~2.5\times, due to the increased ratio of the caustic area relative to the critical area. Additionally, we find that the observed separation between the two main mass components enlarges the critical area by a factor of ~2. These geometrical effects can account for the high number (density) of multiple images observed. We find in numerical simulations, that only ~4% of the clusters (with M_{vir}>6 x 10^{14} h^{-1}solar masses) exhibit as elongated critical curves as M0416. Read more (1335kb, PDF) __________________

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