Minimum variance estimation of statistical anisotropy via galaxy survey
Abstract
We consider the benefits of measuring cosmic statistical anisotropy from redshiftspace correlators of the galaxy number density fluctuation and the peculiar velocity field without adopting the planeparallel (PP) approximation. Since the correlators are decomposed using the general tripolar spherical harmonic (TripoSH) basis, we can deal with wideangle contributions untreatable by the PP approximation, and at the same time, target anisotropic signatures can be cleanly extracted. We, for the first time, compute the covariance of the TripoSH decomposition coefficient and the Fisher matrix to forecast the detectability of statistical anisotropy. The resultant expression of the covariance is free from nontrivial mixings between each multipole moment caused by the PP approximation and hence the detectability is fully optimized. Compared with the analysis under the PP approximation, the superiority in detectability is always confirmed, and it is highlighted, especially in the cases that the shot noise level is large and that target statistical anisotropy has a bluetilted shape in Fourier space. The application of the TripoSHbased analysis to forthcoming allsky survey data could result in constraints on anisotropy comparable to or tighter than the current cosmic microwave background ones.
 Publication:

Journal of Cosmology and Astroparticle Physics
 Pub Date:
 March 2021
 DOI:
 10.1088/14757516/2021/03/039
 arXiv:
 arXiv:2009.04355
 Bibcode:
 2021JCAP...03..039S
 Keywords:

 power spectrum;
 cosmological parameters from LSS;
 galaxy clustering;
 redshift surveys;
 Astrophysics  Cosmology and Nongalactic Astrophysics;
 General Relativity and Quantum Cosmology;
 High Energy Physics  Phenomenology
 EPrint:
 20+1 pages, 3 figures