Abstract
Observations of redshift-space distortions in spectroscopic galaxy surveys offer an attractive method for measuring the build-up of cosmological structure, which depends both on the expansion rate of the Universe and our theory of gravity. Galaxies occupy dark matter halos, whose redshift space clustering has a complex dependence on bias that cannot be inferred from the behavior of matter. We identify two distinct corrections on quasilinear scales (~ 30-80 Mpc/h): the non-linear mapping between real and redshift space positions, and the non-linear suppression of power in the velocity divergence field. We model the first non-perturbatively using the scale-dependent Gaussian streaming model, which we show is accurate at the <0.5 (2) per cent level in transforming real space clustering and velocity statistics into redshift space on scales s>10 (s>25) Mpc/h for the monopole (quadrupole) halo correlation functions. We use perturbation theory to predict the real space pairwise halo velocity statistics. Our fully analytic model is accurate at the 2 per cent level only on scales s > 40 Mpc/h. Recent models that neglect the corrections from the bispectrum and higher order terms from the non-linear real-to-redshift space mapping will not have the accuracy required for current and future observational analyses. Finally, we note that our simulation results confirm the essential but non-trivial assumption that on large scales, the bias inferred from real space clustering of halos is the same one that determines their pairwise infall velocity amplitude at the per cent level.
Highlights
The growth of large-scale structure, as revealed in the clustering of galaxies observed in large redshift surveys, has historically been one of our most important cosmological probes
“quasi-linear” scales, we find a drastic improvement over the model of Matsubara (2008b), which is unsurprising since our model includes real space halo clustering and velocity statistics derived from N-body simulations, and treats the non-linear mapping between real and redshift space nonperturbatively
In contrast to many recent theoretical investigations of redshift space distortions, which have focused on the matter density field and/or performed analyses in Fourier space, in this paper we focus on the redshift space clustering of dark matter halos in configuration space, and use 67.5 h−3 Gpc3 of N-body simulations to make precise measurements of ξ0,2,4 as a function of halo bias
Summary
The growth of large-scale structure, as revealed in the clustering of galaxies observed in large redshift surveys, has historically been one of our most important cosmological probes. In this paper we find a strong dependence on halo bias in the shape of the redshift space correlation function, indicating the need for more sophisticated theoretical models (see Taruya, Saito & Nishimichi 2010, for a Fourierspace approach). We trace this strong bias dependence primarily to the non-linear mapping between real and redshift space. This calculation sets the target for the accuracy of our model.
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