Journal article

Direct shear mapping - a new weak lensing tool

CO de Burgh-Day, EN Taylor, RL Webster, AM Hopkins

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY | OXFORD UNIV PRESS | Published : 2015

Abstract

We have developed a new technique called direct shear mapping (DSM) to measure gravitational lensing shear directly from observations of a single background source. The technique assumes the velocity map of an unlensed, stably rotating galaxy will be rotationally symmetric. Lensing distorts the velocity map making it asymmetric. The degree of lensing can be inferred by determining the transformation required to restore axisymmetry. This technique is in contrast to traditional weak lensing methods, which require averaging an ensemble of background galaxy ellipticity measurements, to obtain a single shear measurement. We have tested the efficacy of our fitting algorithm with a suite of systema..

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University of Melbourne Researchers

Grants

Awarded by Australian Research Council Centre for Excellence for All-Sky Astrophysics (CAASTRO)


Funding Acknowledgements

The referee is thanked for helping to clarify a number of issues in older versions, and contributing greatly to improving the quality of this paper. This research was conducted as part of the Australian Research Council Centre for Excellence for All-Sky Astrophysics (CAASTRO), through project number CE110001020. Special thanks goes to the members of the SAMI instrument and the SAMI survey teams for their advice, input and helpful discussions, in particular, Lisa Fogarty and Scott Croom. We acknowledge support from The University of Melbourne, and the Australian Astronomical Observatory (AAO).