The Subaru FMOS galaxy redshift survey (FastSound). IV. New constraint on gravity theory from redshift space distortions at z ∼ 1.4
Abstract
We measure the redshiftspace correlation function from a spectroscopic sample of 2783 emission line galaxies from the FastSound survey. The survey, which uses the Subaru Telescope and covers a redshift range of 1.19 < z < 1.55, is the first cosmological study at such high redshifts. We detect clear anisotropy due to redshiftspace distortions (RSD) both in the correlation function as a function of separations parallel and perpendicular to the line of sight and its quadrupole moment. RSD has been extensively used to test general relativity on cosmological scales at z < 1. Adopting a ΛCDM cosmology with the fixed expansion history and no velocity dispersion (σ_{v} = 0), and using the RSD measurements on scales above 8 h^{1} Mpc, we obtain the first constraint on the growth rate at the redshift, f (z)σ_{8}(z) = 0.482 ± 0.116 at z ∼ 1.4 after marginalizing over the galaxy bias parameter b(z)σ_{8}(z). This corresponds to 4.2 σ detection of RSD. Our constraint is consistent with the prediction of general relativity fσ_{8} ∼ 0.392 within the 1 σ confidence level. When we allow σ_{v} to vary and marginalize over it, the growth rate constraint becomes fσ _8=0.494^{+0.126}_{0.120}. We also demonstrate that by combining with the lowz constraints on fσ_{8}, highz galaxy surveys like the FastSound can be useful to distinguish modified gravity models without relying on CMB anisotropy experiments.
 Publication:

Publications of the Astronomical Society of Japan
 Pub Date:
 June 2016
 DOI:
 10.1093/pasj/psw029
 arXiv:
 arXiv:1511.08083
 Bibcode:
 2016PASJ...68...38O
 Keywords:

 cosmological parameters;
 cosmology: largescale structure of universe;
 cosmology: observations;
 galaxies: distances and redshifts;
 methods: data analysis;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 23 pages, 20 figures, 1 table, accepted to PASJ