Journal Article

Probing galaxy dark matter haloes in COSMOS with weak lensing flexion

Malin Velander, Konrad Kuijken and Tim Schrabback

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 412, issue 4, pages 2665-2677
Published in print April 2011 | ISSN: 0035-8711
Published online April 2011 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2010.18085.x
Probing galaxy dark matter haloes in COSMOS with weak lensing flexion

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Current theories of structure formation predict specific density profiles of galaxy dark matter haloes, and with weak gravitational lensing we can probe these profiles on several scales. On small scales, higher order shape distortions known as flexion add significant detail to the weak lensing measurements. We present here the first detection of a galaxy–galaxy flexion signal in space-based data, obtained using a new Shapelets pipeline introduced here. We combine this higher order lensing signal with shear to constrain the average density profile of the galaxy lenses in the Hubble Space Telescope Cosmic Evolution Survey (COSMOS). We also show that light from nearby bright objects can significantly affect flexion measurements. After correcting for the influence of lens light, we show that the inclusion of flexion provides tighter constraints on density profiles than does shear alone. Finally we find an average density profile consistent with an isothermal sphere.

Keywords: gravitational lensing: weak; galaxies: haloes; cosmology: observations; dark matter

Journal Article.  9715 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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