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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:
ORCiD logo; ORCiD logo; ORCiD logo;  [1]
  1. (
Publication Date:
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 Kingdom
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; Weak gravitational lensing; Cosmology; Astronomical techniques; Observational cosmology; Gravitational lensing shear

Citation Formats

Kamath, Sowmya, Meyers, Joshua E., Burchat, Patricia R., and LSST Dark Energy Science Collaboration). Shear Measurement Bias Due to Spatially Varying Spectral Energy Distributions in Galaxies. United Kingdom: N. p., 2019. Web. doi:10.3847/1538-4357/ab54cb.
Kamath, Sowmya, Meyers, Joshua E., Burchat, Patricia R., & LSST Dark Energy Science Collaboration). Shear Measurement Bias Due to Spatially Varying Spectral Energy Distributions in Galaxies. United Kingdom. doi:10.3847/1538-4357/ab54cb.
Kamath, Sowmya, Meyers, Joshua E., Burchat, Patricia R., and LSST Dark Energy Science Collaboration). Mon . "Shear Measurement Bias Due to Spatially Varying Spectral Energy Distributions in Galaxies". United Kingdom. doi:10.3847/1538-4357/ab54cb.
@article{osti_1580628,
title = {Shear Measurement Bias Due to Spatially Varying Spectral Energy Distributions in Galaxies},
author = {Kamath, Sowmya and Meyers, Joshua E. and Burchat, Patricia R. and LSST Dark Energy Science Collaboration)},
abstractNote = {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).},
doi = {10.3847/1538-4357/ab54cb},
journal = {The Astrophysical Journal (Online)},
number = 1,
volume = 888,
place = {United Kingdom},
year = {2019},
month = {12}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.3847/1538-4357/ab54cb

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