How to suppress the shot noise in galaxy surveys.
Galaxy surveys are one of the most powerful means to extract cosmological information and for a given volume the attainable precision is determined by the galaxy shot noise sigma(n);(2) relative to the power spectrum P. It is generally assumed that shot noise is white and given by the inverse of the number density n[over ]. In this Letter we argue one may considerably improve upon this due to mass and momentum conservation. We explore this idea with N-body simulations by weighting central halo galaxies by halo mass and find that the resulting shot noise can be reduced dramatically relative to expectations, with a 10-30 suppression at n[over ] = 4x10(-3) (h/Mpc)(3). These results open up new opportunities to extract cosmological information in galaxy surveys and may have important consequences for the planning of future redshift surveys.
Institute for Theoretical Physics, University of Zurich, Zurich 8057, Switzerland.
Uros
U
Seljak
Nico
N
Hamaus
Vincent
V
Desjacques