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Abstract
We present here the cosmoSLICS, a new suite of simulations specially designed for the analysis of current and upcoming weak lensing data beyond the standard twopoint cosmic shear. We sampled the [m;8; h;w0] parameter space at 25 points organised in a Latin hypercube, spanning a range that contains most of the 2 posterior distribution from ongoing lensing surveys. At each of these nodes we evolved a pair of Nbody simulations in which the sampling variance is highly suppressed, and raytraced the volumes
800 times to further increase the eective sky coverage. We extracted a lensing covariance matrix from these pseudoindependent lightcones and show that it closely matches a bruteforce construction based on an ensemble of 800 truly independent Nbody runs. More precisely, a Fisher analysis reveals that both methods yield marginalized twodimensional constraints that vary by less than 6% in area, a result that holds under dierent survey specifications and that matches to within 15% the area obtained from an analytical
covariance calculation. Extending this comparison with our 25 wCDM models, we probed the cosmology dependence of the lensing covariance directly from numerical simulations, reproducing remarkably well the Fisher results from the analytical models at most cosmologies. We demonstrate that varying the cosmology at which the covariance matrix is evaluated in the first place might have an order of magnitude greater impact on the parameter constraints than varying the choice of covariance estimation technique.We present
a test case in which we generate fast predictions for both the lensing signal and its associated variance with a flexible Gaussian process
regression emulator, achieving an accuracy of a few percent on the former and 10% on the latter.
800 times to further increase the eective sky coverage. We extracted a lensing covariance matrix from these pseudoindependent lightcones and show that it closely matches a bruteforce construction based on an ensemble of 800 truly independent Nbody runs. More precisely, a Fisher analysis reveals that both methods yield marginalized twodimensional constraints that vary by less than 6% in area, a result that holds under dierent survey specifications and that matches to within 15% the area obtained from an analytical
covariance calculation. Extending this comparison with our 25 wCDM models, we probed the cosmology dependence of the lensing covariance directly from numerical simulations, reproducing remarkably well the Fisher results from the analytical models at most cosmologies. We demonstrate that varying the cosmology at which the covariance matrix is evaluated in the first place might have an order of magnitude greater impact on the parameter constraints than varying the choice of covariance estimation technique.We present
a test case in which we generate fast predictions for both the lensing signal and its associated variance with a flexible Gaussian process
regression emulator, achieving an accuracy of a few percent on the former and 10% on the latter.
Original language  English 

Article number  A160 
Number of pages  26 
Journal  Astronomy & Astrophysics 
Volume  631 
Early online date  15 Nov 2019 
DOIs  
Publication status  Published  30 Nov 2019 
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Projects
 1 Active

GLOBE: Global Lensing Observations to go Beyond Einstein (027451/1)
1/11/15 → 31/10/21
Project: Research