Nonlinear Information from DESI Luminous Red Galaxies: An Emulator-Based Analysis of Pre- and Post-Reconstruction Power Spectra
/ Authors
Yuting Wang, Gong-Bo Zhao, Kazuya Koyama, Ruiyang Zhao, T. Nishimichi, Zhongxu Zhai, H. Gil-Mar'in, Hanyu Zhang, J. Aguilar, S. Ahlen
and 54 more authors
F. Beutler, D. Bianchi, D. Brooks, F. Castander, T. Claybaugh, A. Cuceu, A. Macorra, A. D. Mattia, B. Dey, P. Doel, D. Eisenstein, S. Ferraro, J. Forero-Romero, E. Gaztañaga, S. Gontcho, Gan Gu, G. Gutierrez, C. Hahn, K. Honscheid, C. Howlett, D. Joyce, S. Juneau, R. Kehoe, D. Kirkby, T. Kisner, J. Kneib, A. Kremin, C. Lamman, M. Landriau, L. Guillou, M. Manera, A. Meisner, R. Miquel, S. Nadathur, J. Newman, E. Paillas, W. Percival, F. Prada, I. P'erez-Rafols, A. J. Rosado-Mar'in, A. Ross, G. Rossi, L. Samushia, E. Sanchez, E. Schlafly, D. Schlegel, M. Schubnell, H. Seo, J. Silber, D. Sprayberry, G. Tarl'e, Xiaoma Wang, B. Weaver, Shuo Yuan
/ Abstract
We present joint measurements of the pre- and post-reconstruction power spectra, $P_{\rm pre}$ and $P_{\rm post}$, together with their cross-power spectrum, $P_{\rm cross}$, for the Luminous Red Galaxies (LRGs) in the DESI Data Release 1 (DR1). We jointly analyse these observables with an emulator-based full-shape modeling framework, thereby, for the first time, we extract complementary nonlinear information from the galaxy density field before and after reconstruction in real survey data. Specifically, including $P_{\rm post}$ and $P_{\rm cross}$ in addition to $P_{\rm pre}$ (hereafter $P_{\rm all}$) yields an improvement of approximately $18$-$27\%$ in the $\sigma_8$ constraint in both $\Lambda$CDM and $w$CDM, depending on the redshift bin, relative to the $P_{\rm pre}$-only analysis with the cosmic microwave background distance priors (hereafter CMB). In $w$CDM, the joint CMB+$P_{\rm all}$ analysis can tighten the constraints on $w$ by approximately $5$-$15\%$ across the two LRG redshift bins, compared to the CMB+$P_{\rm pre}$ combination. Further incorporating the Type Ia supernova dataset and comparing the cosmological constraints in $w$CDM from each individual power-spectrum component with those from the full combination, we find that $P_{\rm all}$ consistently provides the tightest constraints. From the joint CMB+$P_{\rm all}$+DES-Dovekie dataset, we obtain $\Omega_m = 0.314 \pm 0.0048$ and $w = -0.988 \pm 0.023$ for the \texttt{LRG1} sample, and $\Omega_m = 0.318 \pm 0.0046$ and $w = -0.988 \pm 0.025$ for \texttt{LRG2}. These results demonstrate that combining pre- and post-reconstruction power spectra with their cross-correlation enables DESI to harvest additional nonlinear information, leading to tighter constraints on cosmological parameters.