The small-scale linear information in galaxy samples typically lost during
non-linear growth can be restored to a certain level by the density field
reconstruction, which has been demonstrated for improving the precision of the
baryon acoustic oscillations (BAO) measurements. As proposed in the literature,
a joint analysis of the power spectrum before and after the reconstruction
enables an efficient extraction of information carried by high-order
statistics. However, the statistics of the post-reconstruction density field
are difficult to model. In this work, we circumvent this issue by developing an
accurate emulator for the pre-reconstructed, post-reconstructed, and cross
power spectra (Ppre, Ppost, Pcross) up to
k=0.5hMpc−1 based on the \textsc{Dark Quest} N-body simulations.
The accuracy of the emulator is at percent level, namely, the error of the
emulated monopole and quadrupole of the power spectra is less than 1% and
5% of the ground truth, respectively. A fit to an example power spectra
using the emulator shows that the constraints on cosmological parameters get
largely improved using Ppre+Ppost+Pcross with
kmax=0.25hMpc−1, compared to that derived from Ppre alone, namely, the constraints on (Ωm, H0, σ8) are
tightened by ∼41%−55%, and the uncertainties of the derived BAO and RSD
parameters (α⊥, α∣∣, fσ8) shrink by ∼28%−54%, respectively. This highlights the complementarity among Ppre, Ppost and Pcross, which demonstrates the efficiency
and practicability of a joint Ppre, Ppost and Pcross
analysis for cosmological implications.Comment: 15 pages, 8 figures, 2 table