On the bin sensitivity of the transverse BAO

Abstract

The BAO characteristic scale is a useful tool for understanding the evolution of the universe, especially the influence of dark energy on this evolution. In this work, we study the projection effect in transverse BAO, namely the mixing of BAO signals from different epochs caused by $z_c$ uncertainty within a chosen bin. We focus our forecast on two surveys of interest: the Square Kilometre Array (SKA) HI galaxy redshift survey and the Dark Energy Spectroscopic Instrument (DESI)'s final Luminous Red Galaxy (LRG) sample. We test the sensitivity in finding the transverse BAO depending of three bin configurations: a Gaussian, a top-hat and an intermediate of them semi-Gaussian. We also analyse the precision the bin widths $\sigma_z$ from smaller to wider bins $0.01<\sigma_z<0.1$. In order to correct these deviations, we propose a correction based on adjacent redshift to $z_c$, this would provide a semi-statistical correction instead of only relying on fiducial cosmology. Finally, we conclude that despite the higher shot-noise than the top-hat bin separation, the semi-Gaussian bin is the most accurate case to find the BAO signal and to constrain parameters through the angular power spectrum. A Gaussian binning gives the least precise parameter constraints compared to the other two cases.