Validity of the Born approximation for beyond Gaussian weak lensing observables
Abstract
Accurate forward modeling of weak lensing (WL) observables from cosmological parameters is necessary for upcoming galaxy surveys. Because WL probes structures in the nonlinear regime, analytical forward modeling is very challenging, if not impossible. Numerical simulations of WL features rely on ray tracing through the outputs of Nbody simulations, which requires knowledge of the gravitational potential and accurate solvers for light ray trajectories. A less accurate procedure, based on the Born approximation, only requires knowledge of the density field, and can be implemented more efficiently and at a lower computational cost. In this work, we use simulations to show that deviations of the Bornapproximated convergence power spectrum, skewness and kurtosis from their fully raytraced counterparts are consistent with the smallest nontrivial O(Φ ^{3}) postBorn corrections (socalled geodesic and lenslens terms). Our results imply a cancellation among the larger O(Φ ^{4}) (and higher order) terms, consistent with previous analytic work. We also find that cosmological parameter bias induced by the Bornapproximated power spectrum is negligible even for a LSSTlike survey, once galaxy shape noise is considered. When considering higher order statistics such as the κ skewness and kurtosis, however, we find significant bias of up to 2.5σ. Using the LensTools softwaremore »
 Authors:
 Columbia Univ., New York, NY (United States). Dept. of Physics; Brookhaven National Lab. (BNL), Upton, NY (United States). Dept. of Physics
 Columbia Univ., New York, NY (United States). Dept. of Astronomy; New York Univ. (NYU), NY (United States). Dept. of Physics
 Publication Date:
 Research Org.:
 Brookhaven National Laboratory (BNL), Upton, NY (United States)
 Sponsoring Org.:
 USDOE Office of Science (SC), High Energy Physics (HEP) (SC25); National Science Foundation (NSF)
 OSTI Identifier:
 1362165
 Report Number(s):
 BNL1139282017JA
Journal ID: ISSN 24700010; PRVDAQ
 Grant/Contract Number:
 SC0012704; ACI1053575; AST1210877
 Resource Type:
 Journal Article: Accepted Manuscript
 Journal Name:
 Physical Review D
 Additional Journal Information:
 Journal Volume: 95; Journal Issue: 12; Journal ID: ISSN 24700010
 Publisher:
 American Physical Society (APS)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 79 ASTRONOMY AND ASTROPHYSICS; Weak gravitational lensing; Simulations; Methods numerical, analytical, statistical
Citation Formats
Petri, Andrea, Haiman, Zoltan, and May, Morgan. Validity of the Born approximation for beyond Gaussian weak lensing observables. United States: N. p., 2017.
Web. doi:10.1103/PhysRevD.95.123503.
Petri, Andrea, Haiman, Zoltan, & May, Morgan. Validity of the Born approximation for beyond Gaussian weak lensing observables. United States. doi:10.1103/PhysRevD.95.123503.
Petri, Andrea, Haiman, Zoltan, and May, Morgan. 2017.
"Validity of the Born approximation for beyond Gaussian weak lensing observables". United States.
doi:10.1103/PhysRevD.95.123503.
@article{osti_1362165,
title = {Validity of the Born approximation for beyond Gaussian weak lensing observables},
author = {Petri, Andrea and Haiman, Zoltan and May, Morgan},
abstractNote = {Accurate forward modeling of weak lensing (WL) observables from cosmological parameters is necessary for upcoming galaxy surveys. Because WL probes structures in the nonlinear regime, analytical forward modeling is very challenging, if not impossible. Numerical simulations of WL features rely on ray tracing through the outputs of Nbody simulations, which requires knowledge of the gravitational potential and accurate solvers for light ray trajectories. A less accurate procedure, based on the Born approximation, only requires knowledge of the density field, and can be implemented more efficiently and at a lower computational cost. In this work, we use simulations to show that deviations of the Bornapproximated convergence power spectrum, skewness and kurtosis from their fully raytraced counterparts are consistent with the smallest nontrivial O(Φ3) postBorn corrections (socalled geodesic and lenslens terms). Our results imply a cancellation among the larger O(Φ4) (and higher order) terms, consistent with previous analytic work. We also find that cosmological parameter bias induced by the Bornapproximated power spectrum is negligible even for a LSSTlike survey, once galaxy shape noise is considered. When considering higher order statistics such as the κ skewness and kurtosis, however, we find significant bias of up to 2.5σ. Using the LensTools software suite, we show that the Born approximation saves a factor of 4 in computing time with respect to the full ray tracing in reconstructing the convergence.},
doi = {10.1103/PhysRevD.95.123503},
journal = {Physical Review D},
number = 12,
volume = 95,
place = {United States},
year = 2017,
month = 6
}
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