2026/08/06 by Yuting Wang, Ruiyang Zhao, Gong-Bo Zhao +1
Physics and Astronomy · #astro-ph.CO
16 pages, 11 figures
arxiv created 2026/08/06 · arxiv updated 2026/08/07
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 (Pℓ\rm pre, Pℓ\rm post, Pℓ\rm 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\rm max=0.18 h \rm Mpc-1 for P\rm pre and P\rm post, and k\rm max=0.12 h \rm Mpc-1 for P\rm cross.