ABELL 2744 (z=0.308) -------------------- v1.0 referes to products delivered by Aug 31, 2013 Authors: Liliya Williams, Kevin Sebesta, Irshad Mohammed, Jori Liesenborgs, Prasenjit Saha ------------------------------------------------------------------------------------------ BRIEF DESCRIPTION OF THE METHOD: GRALE The method used to do the lensing reconstruction is GRALE, a free-form, adaptive grid method that uses a genetic algorithm to iteratively refine the mass map solution. An initial course grid is populated with a basis set, such as a projected Plummer density profiles. A uniform mass sheet covering the whole modeling region can also be added to supplement the basis set. As the code runs the more dense regions are resolved with a finer grid, with each cell given a Plummer with a proportionate width. The code is started with an initial set of trial solutions. These solutions, as well as all the later evolved ones are evaluated for genetic fitness, and the fit ones are cloned, combined and mutated. The procedure is run until a satisfactory degree of mass resolution is achieved. The final map consists of a superposition of a mass sheet and many Plummers, typically few to several 100, each with its own size and weight, determined by the genetic algorithm. In this release we present 30 such maps for each cluster. Mohammed, I., Liesenborgs, P. Saha, & L.L.R. Williams. 2013, MNRAS, submitted "Mass-Galaxy offsets in Abell 3827, 2218 and 1689: intrinsic properties or line-of-sight substructures?" Liesenborgs, J., de Rijcke, S., Dejonghe, H., Bekaert, P. 2009, MNRAS, 397, 341 "Non-parametric strong lens inversion of SDSS J1004+4112" Liesenborgs, J., de Rijcke, S., Dejonghe, H., Bekaert, P. 2008, MNRAS, 389, 415 "Non-parametric strong lens inversion of Cl 0024+1654: illustrating the monopole degeneracy" Liesenborgs, J., de Rijcke, S., Dejonghe, H. & Bekaert, P. 2007, MNRAS, 380, 1729 "Non-parametric inversion of gravitational lensing systems with few images using a multi-objective genetic algorithm" Liesenborgs, J., de Rijcke, S. & Dejonghe, H. 2006, MNRAS, 367, 1209 "A genetic algorithm for the non-parametric inversion of strong lensing systems" ------------------------------------------------------------------------------------------ DELIVERABLES The directory contains 30 different realizations of the reconstructed cluster mass. The dispersion between the 30 maps is the uncertainty. Because GRALE explores a wide range of lensing degeneracies, the estimated uncertainties are usually larger than in some other methods. (Lensing degeneracies means that many different mass maps can reproduce the same lensed images equally well.) Each reconstruction pixel is about 0.2794 arcsec. The whole grid contained in each file is approximately 200"x200" (see columnes 3 & 4 for exact coordinates), but only the central region, 140"x140", contains calculated kappa, gamma1, gamma2 values. The corresponding pixels are numbered -249 to 250 in both RA & Dec (columns 1 & 2). The rest of the [200arcsec]^2 plane has kappa, gamma1, gamma2 set to -99.0 Coordinates of the central pixel (0,0) are RA = 3.588497560 degrees Dec = -30.396813805 degrees INPUT DATA: SOURCES USED Reconstructions were based on strong lensing data only, with source redshifts as indicated in the table below. Initial multiple image identifications were performed by Zitrin et al. 2009. MNRAS, 396, 1985, with additional input from Adi Zitrin. Below, Merten+11 is Merten et al. 2011, MNRAS, 417, 333. Source z_s Reference 1 2.0 Merten+11 photo-z 1.1 2.0 Merten+11 photo-z 2 2.0 Merten+11 photo-z 2.1 2.0 Merten+11 photo-z 3 4.0 Merten+11 photo-z 4 3.58 Johan Richard spectro-z (unpublished) 5 4.0 Merten+11 photo-z 6 2.019 Johan Richard spectro-z (unpublished) 7 3.0 Dan Coe photo-z 9 2.5 compromise between Merten+11 and Dan Coe photo-z's 10 2.8 Dan Coe photo-z 11 2.5 compromise between Merten+11 and Dan Coe photo-z's We did not use uncertainties on model estimated z_s's because including these made the mass maps worse (as judged by genetic fitness criteria). These maps do not include uncertainties arising from z_s, only those arising from mass reconstruction. NOTE: GRALE does not use any cluster galaxies to do the mass reconstruction; the only observational input are the lensed image positions, their redshifts (listed above), the redshift of the lensing cluster, and the parameters of the standard Lambda CDM. ------------------------------------------------------------------------------------------