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Weak gravitational shear and flexion with polar shapelets.

Authors :
Massey, Richard
Rowe, Barnaby
Refregier, Alexandre
Bacon, David J.
Berg, Joel
Source :
Monthly Notices of the Royal Astronomical Society. 9/1/2007, Vol. 380 Issue 1, p229-245. 17p. 1 Chart, 3 Graphs.
Publication Year :
2007

Abstract

We derive expressions, in terms of ‘polar shapelets’, for the image distortion operations associated with weak gravitational lensing. Shear causes galaxy shapes to become elongated, and is sensitive to the second derivative of the projected gravitational potential along their line of sight; flexion bends galaxy shapes into arcs, and is sensitive to the third derivative. Polar shapelets provide a natural representation, in which both shear and flexion transformations are compact. Through this tool, we understand progress in several weak lensing methods. We then exploit various symmetries of shapelets to construct a range of shear estimators with useful properties. Through an analogous investigation, we also explore several flexion estimators. In particular, some of the estimators can be measured simultaneously and independently for every galaxy, and will provide unique checks for systematics in future weak lensing analyses. Using simulated images from the Shear TEsting Programme, we show that we can recover input shears with no significant bias. A complete software package to parametrize astronomical images in terms of polar shapelets, and to perform a full weak lensing analysis, is available on the Internet. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
00358711
Volume :
380
Issue :
1
Database :
Academic Search Index
Journal :
Monthly Notices of the Royal Astronomical Society
Publication Type :
Academic Journal
Accession number :
26279463
Full Text :
https://doi.org/10.1111/j.1365-2966.2007.12072.x