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The accuracy of weak lensing simulations.

Hilbert, Stefan and Barreira, Alexandre and Fabbian, Giulio and Fosalba, Pablo and Giocoli, Carlo and Bose, Sownak and Calabrese, Matteo and Carbone, Carmelita and Davies, Christopher T. and Li, Baojiu and Llineares, Claudio and Monaco, Pierluigi (2020) 'The accuracy of weak lensing simulations.', Monthly notices of the Royal Astronomical Society., 493 (1). pp. 305-319.


We investigate the accuracy of weak lensing simulations by comparing the results of five independently developed lensing simulation codes run on the same input N-body simulation. Our comparison focuses on the lensing convergence maps produced by the codes, and in particular on the corresponding PDFs, power spectra and peak counts. We find that the convergence power spectra of the lensing codes agree to ≲ 2% out to scales ℓ ≈ 4000. For lensing peak counts, the agreement is better than 5% for peaks with signal-to-noise ≲ 6. We also discuss the systematic errors due to the Born approximation, line-of-sight discretization, particle noise and smoothing. The lensing codes tested deal in markedly different ways with these effects, but they none the less display a satisfactory level of agreement. Our results thus suggest that systematic errors due to the operation of existing lensing codes should be small. Moreover their impact on the convergence power spectra for a lensing simulation can be predicted given its numerical details, which may then serve as a validation test.

Item Type:Article
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Publisher statement:This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2020 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Date accepted:24 January 2020
Date deposited:05 February 2020
Date of first online publication:05 February 2020
Date first made open access:05 February 2020

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