Lensing model of MACS J1149.5+2223 – I. Cluster mass reconstruction

Abstract

Measurements of the total logarithmic central slope of the mass profile in\ngalaxy clusters constrain their evolution and assembly history and that of\ntheir brightest cluster galaxies. We report the first full surface brightness\ndistribution modelling of the inner region of the galaxy cluster MACS\nJ1149.5+2223. We compare these results with a position-based modelling approach\nfor which we employ more than twice the previously known positional\nconstraints. This is the first time that the detailed lensed image\nconfiguration of two non-central cluster galaxies with Einstein rings has been\nmapped. Due to the extended radial coverage provided by the multiple images in\nthis system, we are able to determine the slope $\\partial \\log{ \\kappa\n}/\\partial \\log{R} = -0.33$ of the total projected mass distribution from $8$\nto $80~\\mathrm{kpc}$. This is within the cluster-to-cluster scatter estimates\nfrom previous cluster measurements. Our reconstruction of the image surface\nbrightness distribution of the large central spiral galaxy has a root mean\nsquare residual for all image pixels of $1.14~\\sigma$, where $\\sigma$ is the\nobservational background noise. This corresponds to a reconstruction of the\npositions of bright clumps in the central galaxy with an rms of\n$0.063~\\mathrm{arcsec}$.\n