The Surprisingly Steep Mass Profile of A1689, from a Lensing Analysis of Subaru Images

Publisher Website
Google Scholar
Abstract
Subaru observations of A1689 (z = 0.183) are used to derive an accurate, model-independent mass profile for the entire cluster, r 2 Mpc h-1, by combining magnification bias and distortion measurements. The projected mass profile steepens quickly with increasing radius, falling away to zero at r ~ 1.0 Mpc h-1, well short of the anticipated virial radius. Our profile accurately matches the inner profile, r 200 kpc h-1, derived from deep Hubble Space Telescope Advanced Camera for Surveys (ACS) images. The combined ACS and Subaru information is well fitted by a Navarro-Frenk-White profile with virial mass, (1.93 ± 0.20) × 1015 M☉, and surprisingly high concentration, cvir = 13.7, significantly larger than theoretically expected (cvir 4), corresponding to a relatively steep overall profile. A slightly better fit is achieved with a steep power-law model, d log Σ(θ)/d log θ -3, with a core θc 17 (rc 210 kpc h-1), whereas an isothermal profile is strongly rejected. These results are based on a reliable sample of background galaxies selected to be redder than the cluster E/S0 sequence. By including the faint blue galaxy population, a much smaller distortion signal is found, demonstrating that blue cluster members significantly dilute the true signal for r 400 kpc h-1. This contamination is likely to affect most weak lensing results to date.
All Related Versions

This publication has 17 references indexed in Scilit: