Papers › Improving constraints on primordial non-Gaussianity using neural network based reconstruction

Improving constraints on primordial non-Gaussianity using neural network based reconstruction

11 May 2023arXiv:2305.07018links table onlyarchive 2025-07-28

Thomas Flöss, P. Daniel Meerburg

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We study the use of U-Nets in reconstructing the linear dark matter density field and its consequences for constraining cosmological parameters, in particular primordial non-Gaussianity. Our network is able to reconstruct the initial conditions of redshift z=0 density fields from N-body simulations with 90% accuracy out to k ≤0.4 h/Mpc, competitive with state-of-the-art reconstruction algorithms at a fraction of the computational cost. We study the information content of the reconstructed z=0 density field with a Fisher analysis using the QUIJOTE simulation suite, including non-Gaussian initial conditions. Combining the pre- and post-reconstructed power spectrum and bispectrum data up to kₘₐₓ = 0.52 h/Mpc, we find significant improvements on all parameters. Most notably, we find a factor $3.65$ (local), $3.54$ (equilateral) and $2.90$ (orthogonal) improvement on the marginalized errors of f_(NL) as compared to only using the pre-reconstructed data. We show that these improvements can be attributed to a combination of reduced data covariance and parameter degeneracy. The results constitute an important step towards more optimal inference of primordial non-Gaussianity from non-linear scales.

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tsfloss/DensityFieldTools officialmentioned in paper report
tsfloss/URecon officialmentioned in papertf report
bidenkobd/reconstruction mentioned on GitHubtf report

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