A comparison of the strong lensing properties of the Sersic and the NFW profiles

TL;DR

This paper compares the strong lensing properties of Sersic and NFW profiles, finding that NFW fits can be biased, especially for massive clusters, suggesting the need to include Sersic profiles in lens modeling.

Contribution

It introduces the Sersic profile as an alternative to NFW for lens modeling and analyzes potential biases in NFW parameter estimation.

Findings

NFW profiles can fit lensing constraints but may bias parameters.

For n~2, NFW overestimates mass and underestimates concentration.

Including Sersic profiles improves lensing analysis accuracy.

Abstract

We investigate the strong lensing properties of the Sersic profile as an alternative to the NFW profile, focusing on applications to lens modelling of clusters. Given an underlying Sersic dark matter profile, we study whether an NFW profile can provide an acceptable fit to strong lensing constraints in the form of single or multiple measured Einstein radii. We conclude that although an NFW profile that fits the lensing constraints can be found in many cases, the derived parameters may be biased. In particular, we find that for n~2, which corresponds to massive clusters, the mass at r_200 of the best fit NFW is overestimated (by a factor of ~2) and the concentration is very low (c~2). The differences are important enough to warrant the inclusion of Sersic profile for future analysis of strong lensing clusters.