A Cosmological Full-shape Power Spectra Analysis Using Pre- and Post-reconstructed Density Fields

Abstract In this work, we investigate a joint fitting approach based on theoretical models of power spectra associated with density-field reconstruction. Specifically, we consider the matter auto-power spectra before and after baryon acoustic oscillations (BAO) reconstruction, as well as the cross-power spectrum between the pre- and post-reconstructed density fields. We present redshift-space models for these three power spectra at the one-loop level within the framework of standard perturbation theory, and perform a joint analysis using three types of power spectra, and quantify their impact on parameter constraints. When restricting the analysis to wavenumbers k ≤ 0.2 h Mpc −1 and adopting a smoothing scale of R s = 15 h −1 Mpc, we find that incorporating all three power spectra improves parameter constraints by approximately 11%–16% compared to using only the post-reconstruction power spectrum, with the Figure of Merit increasing by 10.5%. These results highlight the advantages of leveraging multiple power spectra in BAO reconstruction, ultimately enabling more precise cosmological parameter estimation.