TITLE:
The Shear TEsting Programme 2: Factors affecting high precision weak lensing analyses
AUTHOR(S):
Richard Massey, Catherine Heymans, Joel Berge, Gary Bernstein, Sarah Bridle, Douglas Clowe, Hakon Dahle, Richard Ellis, Thomas Erben, Marco
Hetterscheidt, F. William High, Christopher Hirata, Henk Hoekstra, Patrick Hudelot, Mike Jarvis, David Johnston, Konrad Kuijken, Vera Margoniner,
Rachel Mandelbaum, Yannick Mellier, Reiko Nakajima, Stephane Paulin-Henriksson, Molly Peeples, Chris Roat, Alexandre Refregier, Jason Rhodes, Tim
Schrabback, Mischa Schirmer, Uros Seljak, Elisabetta Semboloni, Ludovic Van Waerbeke
DATE:
2006 Aug 29 (MNRAS, submitted);
2006 Aug 30 (arXiv, v1, posted);
2006 Sep 13 (arXiv, v2, posted);
2006 Nov 17 (revised);
2006 Nov 20 (MNRAS, accepted);
2007 Mar 01 (MNRAS, published).
AVAILABILITY:
arXiv astro-ph/0608643 (free);
Blackwell Synergy.
PUBLICATION INFORMATION: Mon. Not. R. Astron. Soc., 376, 13--38, 2007.
ABSTRACT:
The Shear TEsting Programme (STEP) is a collaborative project to improve the accuracy and reliability of weak lensing measurement, in preparation for
the next generation of wide-field surveys. We review sixteen current and emerging shear measurement methods in a common language, and assess their
performance by running them (blindly) on simulated images that contain a known shear signal. We determine the common features of algorithms that most
successfully recover the input parameters. We achieve previously unattained discriminatory precision in our analysis, via a combination of more
extensive simulations, and pairs of galaxy images that have been rotated with respect to each other, thus removing noise from their intrinsic
ellipticities. The robustness of our simulation approach is also confirmed by testing the relative calibration of methods on real data.
Weak lensing measurement has improved since the first STEP paper. Several methods now consistently achieve better than 2% precision, and are still
being developed. However, the simulations can now distinguish all methods from perfect performance. Our main concern continues to be the potential for
a multiplicative shear calibration bias: not least because this can not be internally calibrated with real data. We determine which galaxy populations
are responsible and, by adjusting the simulated observing conditions, we also investigate the effects of instrumental and atmospheric parameters. We
have isolated several previously unrecognised aspects of galaxy shape measurement, in which focussed development could provide further progress towards
the sub-percent level of precision desired for future surveys. [ABRIDGED]
ADS BIBLIOGRAPHIC CODE: 2007MNRAS.376...13M
COMMENTS: This is a follow-up to the first STEP program (astro-ph/0506112; note that I was not part of STEP1).