Largest scales from the largest galaxy surveys: the pseudo Karhunen-Loève method

Abstract

The increasing area and depth of galaxy surveys will give us access to the largest scales in the Universe and allow for a direct test of the primordial power spectrum set by inflation. To take full advantage of the survey's volume, we must deal with redshift space distortions, growth of structure along the line of sight, luminosity-dependent bias, wide-angle effects and complex galaxy selection functions. We present a thorough description of the pseudo Karhunen-Loève method for measuring galaxy clustering, a method particularly well-tuned for the largest scales, and extend its applicability and power by taking into account light-cone effects, galaxy bias evolution, and by generalizing it to anisotropic selection functions. We also show that the combination of non-overlapping surveys result in more information than the sum of its parts and that clustering amplitude evolution along the line of sight, both due to galaxy bias and structure growth, must be taken into account at scales beyond the turn-over.