BAO from angular clustering: optimization and mitigation of theoretical systematics
Abstract
We study the methodology and potential theoretical systematics of measuring Baryon Acoustic Oscillations (BAO) using the angular correlation functions in tomographic bins. We calibrate and optimize the pipeline for the Dark Energy Survey Year 1 dataset using 1800 mocks. We compare the BAO fitting results obtained with three estimators: the Maximum Likelihood Estimator (MLE), Profile Likelihood, and Markov Chain Monte Carlo. The fit results from the MLE are the least biased and their derived 1- error bar are closest to the Gaussian distribution value after removing the extreme mocks with non-detected BAO signal. We show that incorrect assumptions in constructing the template, such as mismatches from the cosmology of the mocks or the underlying photo- errors, can lead to BAO angular shifts. We find that MLE is the method that best traces this systematic biases, allowing to recover the true angular distance values. In a real survey analysis, it may happen that the final data sample properties are slightly different from those of the mock catalog. We show that the effect on the mock covariance due to the sample differences can be corrected with the help of the Gaussian covariance matrix or more effectively using the eigenmode expansion of the mock covariance. In the eigenmode expansion, the eigenmodes are provided by some proxy covariance matrix. The eigenmode expansion is significantly less susceptible to statistical fluctuations relative to the direct measurements of the covariance matrix because of the number of free parameters is substantially reduced
Keywords
Cite
@article{arxiv.1801.04390,
title = {BAO from angular clustering: optimization and mitigation of theoretical systematics},
author = {K. C. Chan and M. Crocce and A. J. Ross and S. Avila and J. Elvin-Poole and M. Manera and W. J. Percival and R. Rosenfeld and T. M. C. Abbott and F. B. Abdalla and S. Allam and E. Bertin and D. Brooks and D. L. Burke and A. Carnero Rosell and M. Carrasco Kind and J. Carretero and F. J. Castander and C. E. Cunha and C. B. D'Andrea and L. N. da Costa and C. Davis and J. De Vicente and T. F. Eifler and J. Estrada and B. Flaugher and P. Fosalba and J. Frieman and J. García-Bellido and E. Gaztanaga and D. W. Gerdes and D. Gruen and R. A. Gruendl and J. Gschwend and G. Gutierrez and W. G. Hartley and K. Honscheid and B. Hoyle and D. J. James and E. Krause and K. Kuehn and O. Lahav and M. Lima and M. March and F. Menanteau and C. J. Miller and R. Miquel and A. A. Plazas and K. Reil and A. Roodman and E. Sanchez and V. Scarpine and I. Sevilla-Noarbe and M. Smith and M. Soares-Santos and F. Sobreira and E. Suchyta and M. E. C. Swanson and G. Tarle and D. Thomas and A. R. Walker},
journal= {arXiv preprint arXiv:1801.04390},
year = {2018}
}
Comments
23 pages, 23 figs, match to the published version