Extracting key information from spectroscopic galaxy surveys

We develop a novel method to extract key cosmological information, which is primarily carried by the baryon acoustic oscillations (BAO) and redshift space distortions (RSD), from spectroscopic galaxy surveys based on a joint principal component analysis (PCA) and massive optimized parameter estimation and data compression (MOPED) algorithm. We apply this method to galaxy samples from BOSS DR12, and find that a PCA manipulation is effective at extracting the informative modes in the 2D correlation function ξ(s, μ), giving a tighter constraint on BAO and RSD parameters compared to that using the lowest three multipole moments by the traditional method; i.e. the figure of merit of BAO and RSD parameters is improved by 17 per cent. We then perform a compression of the informative PC modes for BAO and RSD parameters using the MOPED scheme, reducing the dimension of the data vector to the number of interesting parameters, manifesting the joint PCA and MOPED as a powerful tool for clustering analysis with almost no loss of constraining power.