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Shapelets “Multiple Multipole” Shear Measurement

Published online by Cambridge University Press:  15 June 2005

Richard Massey
Affiliation:
California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, U.S.A. email: rjm@astro.caltech.edu
Alexandre Refregier
Affiliation:
Service d'Astrophysique, Bât. 709, CEA Saclay, F-9119 Gif sur Yvette,France
David Bacon
Affiliation:
Institute for Astronomy, Blackford Hill, Edinburgh EH9 3HJ, U.K.
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Abstract

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The measurement of weak gravitational lensing is currently limited to a precision of $\sim$10% by instabilities in galaxy shape measurement techniques and uncertainties in their calibration. The potential of large, on-going and future cosmic shear surveys will only be realised with the development of more accurate image analysis methods. We present a description of several possible shear measurement methods using the linear “shapelets” decomposition. Shapelets provides a complete reconstruction of any galaxy image, including higher-order shape moments that can be used to generalise the KSB method to arbitrary order. Many independent shear estimators can then be formed for each object, using linear combinations of shapelet coefficients. These estimators can be treated separately, to improve their overall calibration; or combined in more sophisticated ways, to eliminate various instabilities and a calibration bias. We apply several methods to simulated astronomical images containing a known input shear, and demonstrate the dramatic improvement in shear recovery using shapelets. A complete IDL software package to perform image analysis and manipulation in shapelet space can be downloaded from www.astro.caltech.edu/~rjm/shapelets/.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

Type
Contributed Papers
Copyright
© 2004 International Astronomical Union