TITLE:
Systematic errors in weak lensing: application to SDSS galaxy-galaxy weak lensing.
AUTHOR(S):
Rachel Mandelbaum1,
Christopher M. Hirata1,
Uros Seljak1,2,
Jacek Guzik3,4,
Nikhil Padmanabhan1,
Cullen Blake5,
Michael R. Blanton6,
Robert Lupton1,
Jonathan Brinkmann7
(1Princeton Univ.;
2ICTP;
3Jagiellonian Univ.;
4U. of Pennsylvania;
5CfA;
6NYU;
7Apache Point Obs.)
DATE:
2005 Jan 12 (arXiv, v1, posted);
2005 Jan 12 (MNRAS, submitted);
2005 Mar 27 (revised);
2005 Jun 02 (MNRAS, accepted);
2005 Jul 15 (MNRAS, published).
AVAILABILITY:
arXiv astro-ph/0501201 (free); Blackwell Synergy (requires
subscription).
PUBLICATION INFORMATION: Monthly Notices of the Royal Astronomical Society, 361,
1287--1322 (2005), 36 pages.
ABSTRACT:
Weak lensing is emerging as a powerful observational tool to constrain cosmological models, but is at present limited by an incomplete
understanding of many sources of systematic error. Many of these errors are multiplicative and depend on the population of background
galaxies. We show how the commonly cited geometric test, which is rather insensitive to cosmology, can be used as a ratio test of
systematics in the lensing signal at the 1 per cent level. We apply this test to the galaxy-galaxy lensing analysis of the Sloan
Digital Sky Survey (SDSS), which at present is the sample with the highest weak lensing signal to noise and has the additional
advantage of spectroscopic redshifts for lenses. This allows one to perform meaningful geometric tests of systematics for different
subsamples of galaxies at different mean redshifts, such as brighter galaxies, fainter galaxies and high-redshift luminous red
galaxies, both with and without photometric redshift estimates. We use overlapping objects between SDSS and the DEEP2 and 2SLAQ
spectroscopic surveys to establish accurate calibration of photometric redshifts and to determine the redshift distributions for SDSS.
We use these redshift results to compute the projected surface density contrast DeltaSigma around 259 609 spectroscopic galaxies in
the SDSS; by measuring DeltaSigma with different source samples we establish consistency of the results at the 10 per cent level
(1-sigma). We also use the ratio test to constrain shear calibration biases and other systematics in the SDSS survey data to determine
the overall galaxy-galaxy weak lensing signal calibration uncertainty. We find no evidence of any inconsistency among many subsamples
of the data.
ADS BIBLIOGRAPHIC CODE: 2005MNRAS.361.1287M
COMMENTS:
SDSS Publication #472.