Title: Shear Measurement Bias Due to Spatially Varying Spectral Energy Distributions in Galaxies

Abstract

Galaxy color gradients (CGs)—i.e., spectral energy distributions that vary across the galaxy profile—will impact galaxy shape measurements when the modeled point-spread function (PSF) corresponds to that for a galaxy with spatially uniform color. This paper describes the techniques and results of a study of the expected impact of galaxy CGs on weak lensing measurements with the Large Synoptic Survey Telescope (LSST) when the PSF size depends on wavelength. The bias on cosmic shear measurements from CGs is computed both for parametric bulge+disk galaxy simulations and for more realistic chromatic galaxy surface brightness profiles based on Hubble Space Telescope V- and I-band images in the All-Wavelength Extended Groth Strip International Survey (AEGIS). For the parametric galaxies, and for the more realistic galaxies derived from AEGIS galaxies with a sufficient signal-to-noise ratio that CG bias can be isolated, the predicted multiplicative shear biases due to CGs are found to be at least a factor of two below the LSST full-depth requirement on the total systematic uncertainty in the redshift-dependent shear calibration. The analysis code and data products are publicly available (https://github.com/sowmyakth/measure_cg_bias).

Authors:

Kamath, Sowmya ;

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• Search DOE PAGES for ORCID "0000-0003-0443-8221"
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Meyers, Joshua E. ;

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• Search DOE PAGES for ORCID "0000-0002-2308-4230"
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Burchat, Patricia R. ;

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• Search DOE PAGES for ORCID "0000-0001-5004-3736"
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LSST Dark Energy Science Collaboration) ^[1]

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Publication Date:

2019-12-30

Research Org.:

Stanford Univ., CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)

Sponsoring Org.:

USDOE Office of Science (SC), High Energy Physics (HEP); National Science Foundation (NSF); Centre National de la Recherche Scientifique; USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR); USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities Division; USDOE National Nuclear Security Administration (NNSA); Science and Technology Facilities Council (STFC); LSST Corporation; Centre National de la Recherche Scientifique (CNRS); GridPP Collaboration

Contributing Org.:

LSST Dark Energy Science Collaboration

OSTI Identifier:

1580628

Alternate Identifier(s):

OSTI ID: 1594524; OSTI ID: 1604566; OSTI ID: 1682519; OSTI ID: 1767406

Report Number(s):

LLNL-JRNL-805921
Journal ID: ISSN 1538-4357

Grant/Contract Number:  

SC0019351; AC02-05CH11231; AC02-76SF00515; PHY-1404070; AC52-07NA27344; C0019351

Resource Type:

Published Article

Journal Name:

The Astrophysical Journal (Online)

Additional Journal Information:

Journal Name: The Astrophysical Journal (Online) Journal Volume: 888 Journal Issue: 1; Journal ID: ISSN 1538-4357

Publisher:

Institute of Physics (IOP)

Country of Publication:

United States

Language:

English

Subject:

79 ASTRONOMY AND ASTROPHYSICS; Weak gravitational lensing; Cosmology; Astronomical techniques; Observational cosmology; Gravitational lensing shear