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Title

Shape, shear and flexion: an analytic flexion formalism for realistic mass profiles

Author(s)

Lasky, P. D.;  Fluke, C. J.

Abstract

Flexion is a non-linear gravitational lensing effect that arises from gradients in the convergence and shear across an image. We derive a formalism that describes non-linear gravitational lensing by a circularly symmetric lens in the thin-lens approximation. This provides us with relatively simple expressions for first- and second-flexion in terms of only the surface density and projected mass distribution of the lens. We give details of exact lens models, in particular providing flexion calculations for a Sersic-law profile, which has become increasingly popular over recent years. We further provide a single resource for the analytic forms of convergence, shear, first- and second-flexion for the following mass distributions: a point mass, singular isothermal sphere (SIS); Navarro-Frenk-White (NFW) profile; Sersic-law profile. We quantitatively compare these mass distributions and show that the convergence and first-flexion are better indicators of the Sersic shape parameter, while for the concentration of NFW profiles the shear and second-flexion terms are preferred.

Publication type

Journal article

Research centre

Swinburne University of Technology. Faculty of Information and Communication Technologies. Centre for Astrophysics and Supercomputing

Source

Monthly Notices of the Royal Astronomical Society, Vol. 396, no. 4 (Jul 2009), pp. 2257-2268

Publication year

2009

FOR Code(s)

0201 Astronomical and Space Sciences

Keyword(s)

Dark matter;  Galaxy haloes;  Gravitational lensing

Publisher

Wiley-Blackwell Publishing

ISSN

0035-8711

Publisher URL

http://dx.doi.org/10.1111/j.1365-2966.2009.14888.x

Copyright

Copyright © 2009 The Authors. Journal compilation copyright © 2009 Royal Astronomical Society. The accepted manuscript is reproduced in accordance with the copyright policy of the publisher. The definitive publication is available at www.interscience.wiley.com.

Research Projects

The Commonwealth cosmology initiative: from the first objects to the cosmic web, Australian Research Council grant number DP0665574

Full text

Peer reviewed