SIMBAD references

Haloes formed in the standard Λ cold dark matter framework should follow a universal mass density profile and fit a well-defined mass–concentration relation. Lensing analyses of clusters with a large Einstein radius seem to contradict this scenario, with the massive cluster Abell 1689 being often claimed as a notable example of a highly over-concentrated halo. Shape and orientation biases in lensing studies might be on the basis of this disagreement between theory and observations. We developed a method for a full three-dimensional analysis of strong- and weak-lensing data. Surface density maps estimated from lensing are deprojected to infer the actual triaxial structure of the cluster, whose mass distribution is approximated as an ellipsoidal Navarro–Frenk–White halo with arbitrary orientation. Inversion is performed under competing a priori assumptions, integrated in the method, thanks to Bayesian statistics. We applied the method to Abell 1689. Whatever the considered priors on shape and orientation, both weak- and strong-lensing analyses found the halo to be slightly over-concentrated but still consistent with theoretical predictions. We found some evidence for a mildly-triaxial lens (minor-to-major-axis ratio ∼ 0.5±0.2) with the major-axis orientated along the line of sight. Exploiting priors from N-body simulations, we found mass M₂₀₀= (1.3±0.4) {x} 10¹⁵ M_☉ and concentration c₂₀₀= 10 ± 3 for the weak-lensing analysis of Subaru data, M₂₀₀= (1.7±0.3) {x} 10¹⁵ M_☉ and c₂₀₀= 6.1±0.9 for the strong-lensing analysis of multiple-image systems, and M₂₀₀= (1.3±0.2) {x} 10¹⁵ M_☉ and c₂₀₀= 7.3±0.8 for the combined weak- plus strong-lensing analysis.

Based in part on data collected at the Subaru Telescope, which is operated by the National Astronomical Society of Japan.