Local Nonlinear Transforms Effectively Extract Cosmological Information From Large-Scale Structure

Abstract

Extracting cosmological information from nonlinear and non-Gaussian large-scale structure remains a major challenge. We introduce the (Zel'dovich-inspired) ZI transform, a simple one-parameter local nonlinear transform in which $\hat{I}\cdot$ controls the weighting of higher-order information in the transformed density field. For $\hat{I}\cdot \ge 3$, the transform can substantially suppress gravitational non-Gaussianity. Using the \textsc{Quijote} suite and Fisher information analysis over summed neutrino mass $M_{\hat{I}}½$, primordial non-Gaussianity $f_{\mathrm{NL}}$ with different shapes, and $\hat{I}›$CDM parameters, we find that the joint data vector of three transformed-field power spectra with $\{\hat{I}\cdot =\infty ,6,3\}$, denoted $P_{\mathrm{ZI}}$, tightens all constraints relative to the ordinary power spectrum, especially boosting the constraining power by factors of $290$ for $f_{\mathrm{NL}}^{\mathrm{local}}$ and $107$ for $M_{\hat{I}}½$, while yielding nearly unbiased parameter estimates. Compared further with other statistics beyond the ordinary power spectrum, $P_{\mathrm{ZI}}$ stands out as a powerful cosmological probe.

9 pages, 7 figures, 3 tables; comments welcomed