Forecasting cosmological constraints from the nonlinear halo density field with Zel'dovich-inspired transform

Abstract

The Zel'dovich-inspired (ZI) transform is a local nonlinear transform of the density field that can Gaussianize the late-time matter field and recover information from higher-order $N$-point correlation functions through its power spectrum, with the parameter $\eta$ controlling the weighting of higher-order information. Using Fisher-matrix analyses of halo catalogs from the Quijote and Quijote-PNG simulations, we study the redshift-space monopole power spectrum of the ZI-transformed halo density field. The joint statistic $P_{\mathrm{ZI},0}$, constructed from three representative transforms with $\eta =1$, $10$, and $+\infty$, yields substantially tighter constraints than the conventional halo power spectrum $P_{\mathrm{h},0}$ on standard cosmological parameters, the summed neutrino mass, and primordial non-Gaussianity amplitudes, while outperforming the marked power spectrum for many parameters. We further calibrate a scale-dependent noise correction for the ZI power spectrum, with an effective noise amplitude that depends on wavenumber, and find that the correction further tightens the constraints. In particular, the noise-corrected $P_{\mathrm{ZI},0}$ improves the constraints on $f_{\mathrm{NL}}^{\mathrm{equil}}$, $f_{\mathrm{NL}}^{\mathrm{ortho}}$, $M_{\nu }$, and $n_{\mathrm{s}}$ by factors of $5.6$, $5.5$, $5.2$, and $5.8$, respectively, relative to $P_{\mathrm{h},0}$. These results demonstrate the potential of ZI power spectra as a complement to standard two-point statistics for extracting nonlinear cosmological information. Our forecasts may be conservative because the halo catalogs have substantially lower number densities than those expected from forthcoming galaxy surveys.

18 pages, 12 figures