The accuracy of weak lensing simulations

Hilbert, Stefan; Barreira, Alexandre; Fabbian, Giulio; Fosalba, P.; Giocoli, Carlo; Bose, Sownak; Calabrese, Matteo; Carbone, C.; Davies, Christopher T.; Li, Baojiu; Llinares, Claudio; Monaco, Pierluigi

doi:10.1093/mnras/staa281

Cited by 34 publications

(30 citation statements)

References 120 publications

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“…We note that on scales smaller than ∼5 arcmin the results from TREECORR appear to be biased slightly low to those from the direct estimator approach. We furthermore note a difference between the theoretical prediction and the measurements for small aperture radii which is due to shot noise and the line-of-sight discretization from which the simulated data suffers (Hilbert et al 2020).…”

Section: Analysis Of the Cfhtlens Mock Skiesmentioning

confidence: 83%

“…Right-hand panel: Shows the same as the left-hand panel, except this time the estimates from the direct estimator have been computed in bins of aperture completeness. The difference between the simulations and the theoretical predictions for small aperture radii can be attributed to shot noise and the line-of-sight discretization from which the simulated data suffers (Hilbert et al 2020). method.…”

Section: Analysis Of the Cfhtlens Mock Skiesmentioning

confidence: 88%

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Fast estimation of aperture mass statistics – I. Aperture mass variance and an application to the CFHTLenS data

Porth

Smith

Simon

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We explore an alternative method to the usual shear correlation function approach for the estimation of aperture mass statistics in weak lensing survey data. Our approach builds on the direct estimator method. In this paper, to test and validate the methodology, we focus on the aperture mass dispersion. After computing the signal and noise for a weighted set of measured ellipticites we show how the direct estimator can be made into a linear order algorithm that enables a fast and efficient computation. We then investigate the applicability of the direct estimator approach in the presence of a real survey mask with holes and chip gaps. For this we use a large ensemble of full ray-tracing mock simulations. By using various weighting schemes for combining information from different apertures we find that inverse variance weighting the individual aperture estimates with an aperture completeness greater than 70% yields an answer that is in close agreement with the correlation function approach. We then apply this approach to the CFHTLenS as a pilot scheme and find that our method recovers to high accuracy the official result for the variance of both the E and B mode signal. We then explore the cosmological information content of the direct estimator using the Fisher information approach. We show that there is a only modest loss in cosmological information from the rejection of apertures that are of low completeness. This method unlocks the door to efficient methods for recovering higher order aperture mass statistics in linear order operations.

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Section: Analysis Of the Cfhtlens Mock Skiesmentioning

confidence: 83%

Section: Analysis Of the Cfhtlens Mock Skiesmentioning

confidence: 88%

Fast estimation of aperture mass statistics – I. Aperture mass variance and an application to the CFHTLenS data

Porth

Smith

Simon

et al. 2020

Monthly Notices of the Royal Astronomical Society

Self Cite

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“…The Magneticum past light-cone reconstructions are performed using the Simulation LIght conE buildeR codeslicer 2closely following the pipeline presented in Castro et al (2018) and forked from a MapSim branch (Giocoli et al 2015(Giocoli et al , 2018bHilbert et al 2020). Briefly, light-cones are built in post-processing, assigning particles to predetermined 2D mass maps according to the triangular-shaped cloud mass assignment scheme.…”

Section: Past Light-cone Reconstructionmentioning

confidence: 99%

Impact of baryons in cosmic shear analyses with tomographic aperture mass statistics

Martinet

Castro

Harnois-Déraps

et al. 2021

A&A

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NonGaussian cosmic shear statistics based on weak-lensing aperture mass (Map) maps can outperform the classical shear two-point correlation function (γ-2PCF) in terms of cosmological constraining power. However, reaching the full potential of these new estimators requires accurate modeling of the physics of baryons as the extra nonGaussian information mostly resides at small scales. We present one such modeling based on the Magneticum hydrodynamical simulation for the KiDS-450 and DES-Y1 surveys and a Euclid-like survey. We compute the bias due to baryons on the lensing PDF and the distribution of peaks and voids in Map maps and propagate it to the cosmological forecasts on the structure growth parameter S8, the matter density parameter Ωm, and the dark energy equation of state w0 using the SLICS and cosmo-SLICS sets of dark-matter-only simulations. We report a negative bias of a few percent on S8 and Ωm and also measure a positive bias of the same level on w0 when including a tomographic decomposition. These biases reach ∼5% when combining Map statistics with the γ-2PCF as these estimators show similar dependency on the AGN feedback. We verify that these biases constitute a less than 1σ shift on the probed cosmological parameters for current cosmic shear surveys. However, baryons need to be accounted for at the percentage level for future Stage IV surveys and we propose to include the uncertainty on the AGN feedback amplitude by marginalizing over this parameter using multiple simulations such as those presented in this paper. Finally, we explore the possibility of mitigating the impact of baryons by filtering the Map map but find that this process would require suppressing the small-scale information to a point where the constraints would no longer be competitive.

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“…The Magneticum past light-cone reconstructions are performed using the Simulation LIght conE buildeR code -SLICER 2 -closely following the pipeline presented in Castro et al (2018) and forked from a MapSim branch (Giocoli et al 2015(Giocoli et al , 2018aHilbert et al 2020). Shortly, light-cones are built in post-processing, assigning particles to predetermined 2D mass maps according to the triangular-shaped cloud mass assignment scheme.…”

Section: Past Light-cone Reconstructionmentioning

confidence: 99%

Impact of baryons in cosmic shear analyses with tomographic aperture mass statistics

Martinet,

Castro,

Harnois-Déraps

et al. 2020

Preprint

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Non-Gaussian cosmic shear statistics based on weak-lensing aperture mass (M ap ) maps can outperform the classical shear two-point correlation function (γ-2PCF) in terms of cosmological constraining power. Reaching the full potential of these new estimators however requires an accurate modeling of the physics of baryons as the extra non-Gaussian information mostly reside at small scales. We present one such modeling based on the Magneticum hydrodynamical simulation for the KiDS-450, DES-Y1, and a Euclid-like surveys. We compute the bias due to baryons on the lensing PDF and the distribution of peaks and voids in M ap maps and propagate it to the cosmological forecasts on the structure growth parameter S 8 , the matter density parameter Ω m and the dark energy equation of state w 0 , using the SLICS and cosmo-SLICS sets of dark matter only simulations. We report a negative bias of a few percents on S 8 and Ω m and also measure a positive bias of the same level on w 0 when including a tomographic decomposition. These biases are increased to the order of ∼ 5% when combining M ap statistics with the γ-2PCF as these estimators show similar dependency on the AGN feedback. We verify that these biases constitute less than a 1σ shift on the probed cosmological parameters for current cosmic shear surveys. Baryons, however, need to be accounted for at the percent level for future Stage IV surveys and we propose to include uncertainty on the AGN feedback amplitude by marginalizing over this parameter using multiple simulations such as those presented in this paper. Finally, we explore the possibility of mitigating the impact of baryons by filtering the M ap map but find that this process would require to suppress the small-scale information to a point where the constraints would no longer be competitive.

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The accuracy of weak lensing simulations

Cited by 34 publications

References 120 publications

Fast estimation of aperture mass statistics – I. Aperture mass variance and an application to the CFHTLenS data

Fast estimation of aperture mass statistics – I. Aperture mass variance and an application to the CFHTLenS data

Impact of baryons in cosmic shear analyses with tomographic aperture mass statistics

Impact of baryons in cosmic shear analyses with tomographic aperture mass statistics

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