The Impact of Wrong Assumptions in BAO Reconstruction

TL;DR

This paper analytically examines how incorrect assumptions during BAO reconstruction affect the power spectrum, finding minimal impact on peak location but potential biases in shape and quadrupole amplitude that could influence future cosmological parameter estimates.

Contribution

It provides a theoretical framework to quantify the effects of wrong assumptions in BAO reconstruction, highlighting potential biases and proposing solutions.

Findings

BAO peak location shifts negligibly with wrong assumptions

Shape of BAO peak can be affected at the percent level

Quadrupole amplitude may be biased by about five percent

Abstract

The process of density field reconstruction enhances the statistical power of distance scale measurements using baryon acoustic oscillations (BAO). During this process a fiducial cosmology is assumed in order to convert sky coordinates and redshifts into distances; fiducial bias and redshift-space-distortion parameters are also assumed in this procedure. We analytically assess the impact of incorrect cosmology and bias assumptions on the post-reconstruction power spectra using low-order Lagrangian perturbation theory, deriving general expressions for the incorrectly reconstructed spectra. We find that the BAO peak location appears to shift only by a negligible amount due to wrong assumptions made during reconstruction. However, the shape of the BAO peak and the quadrupole amplitude can be affected by such errors (at the percent- and five-percent-level respectively), which potentially could cause small biases in parameter inference for future surveys; we outline solutions to such complications.