A Gaussian covariance matrix for joint pre- and post-reconstruction full-shape power spectrum analysis
Year: 2026
Type: article
Abstract: We apply the Gaussian covariance formalism to develop a semi-analytical covariance model for the joint analysis of pre-reconstruction, post-reconstruction, and cross full-shape galaxy power spectra. We model the reconstruction-reduced, scale-dependent cross shot noise using displacement-field statistics and introduce a new estimator that directly measures this term. Using the measured power spectra and the modeled shot-noise predictions as inputs, we construct the Gaussian covariance while accounting for correlations between the pre- and post-reconstruction density fields. We validate the resulting semi-analytical Gaussian covariance against mock catalogues. Using emulator-based parameter inference, we demonstrate that the semi-analytical Gaussian covariance adequately captures the dominant contribution to the covariance structure of the full data vector ( P ℓ pre , P ℓ post , P ℓ cross ). For the joint fit to these three power spectra, it yields cosmological constraints consistent with those obtained using the mock-based numerical covariance over the adopted fitting ranges: k max = 0.18 h Mpc -1 for P pre and P post , and k max = 0.12 h Mpc -1 for P cross .
Institutions: Chinese Academy of Sciences, National Astronomical Observatories, Tsinghua University, University of Chinese Academy of Sciences, Kavli Institute for the Physics and Mathematics of the Universe, Kyoto University, Yukawa Institute for Theoretical Physics, University of Portsmouth, The University of Tokyo
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,290
OpenAlex ID: W7201861928