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Weak-lensing Peak Finding: Estimators, Filters, and Biases

Schmidt, Fabian and Rozo, Eduardo (2011) Weak-lensing Peak Finding: Estimators, Filters, and Biases. Astrophysical Journal, 735 (2). Art. No. 119. ISSN 0004-637X.

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Large catalogs of shear-selected peaks have recently become a reality. In order to properly interpret the abundance and properties of these peaks, it is necessary to take into account the effects of the clustering of source galaxies, among themselves and with the lens. In addition, the preferred selection of magnified galaxies in a flux- and size-limited sample leads to fluctuations in the apparent source density that correlate with the lensing field. In this paper, we investigate these issues for two different choices of shear estimators that are commonly in use today: globally normalized and locally normalized estimators. While in principle equivalent, in practice these estimators respond differently to systematic effects such as magnification and cluster member dilution. Furthermore, we find that the answer to the question of which estimator is statistically superior depends on the specific shape of the filter employed for peak finding; suboptimal choices of the estimator+filter combination can result in a suppression of the number of high peaks by orders of magnitude. Magnification and size bias generally act to increase the signal-to-noise ν of shear peaks; for high peaks the boost can be as large as Δν ≈ 1-2. Due to the steepness of the peak abundance function, these boosts can result in a significant increase in the observed abundance of shear peaks. A companion paper investigates these same issues within the context of stacked weak-lensing mass estimates.

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Additional Information:© 2011 American Astronomical Society. Received 2010 September 14; accepted 2011 April 11; published 2011 June 24. We thank Richard Ellis, Richard Massey, James Taylor, and Scott Dodelson for helpful discussions. F.S. is supported by the Gordon and Betty Moore Foundation at Caltech. E.R. is funded by NASA through the Einstein Fellowship program, grant PF9-00068.
Group:Moore Center for Theoretical Cosmology and Physics
Funding AgencyGrant Number
Gordon and Betty Moore FoundationUNSPECIFIED
NASA Einstein Fellowship programPF9-00068
Subject Keywords:gravitational lensing: weak
Issue or Number:2
Classification Code:PACS: 98.65.Cw; 98.80.Cq; 98.62.Sb; 98.62.Gq
Record Number:CaltechAUTHORS:20110712-113548421
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Official Citation:Weak-lensing Peak Finding: Estimators, Filters, and Biases Fabian Schmidt and Eduardo Rozo 2011 ApJ 735 119
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:24382
Deposited By: Jason Perez
Deposited On:12 Jul 2011 22:23
Last Modified:03 Oct 2019 02:55

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