The Subaru FMOS galaxy redshift survey (FastSound). IV. New constraint on gravity theory from redshift space distortions at z ∼ 1.4

Journal article

We measure the redshift-space correlation function from a spectroscopic sample of 2783 emission line galaxies from the FastSound survey. The survey, which uses the Subaru Telescope and covers the redshift ranges of $1.19<$z$<1.55$, is the first cosmological study at such high redshifts. We detect clear anisotropy due to redshift-space 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 LCDM cosmology with the fixed expansion history and no velocity dispersion $\sigma_{\rm v}=0$, and using the RSD measurements on scales above 8Mpc/h, we obtain the first constraint on the growth rate at the redshift, $f(z)\sigma_8(z)=0.482\pm 0.116$ at $z\sim 1.4$ after marginalizing over the galaxy bias parameter $b(z)\sigma_8(z)$. This corresponds to $4.2\sigma$ detection of RSD. Our constraint is consistent with the prediction of general relativity $f\sigma_8\sim 0.392$ within the $1-\sigma$ confidence level. When we allow $\sigma_{\rm v}$ to vary and marginalize it over, the growth rate constraint becomes $f\sigma_8=0.494^{+0.126}_{-0.120}$. We also demonstrate that by combining with the low-z constraints on $f\sigma_8$, high-z galaxy surveys like the FastSound can be useful to distinguish modified gravity models without relying on CMB anisotropy experiments.

Authors: Okumura, T; Hikage, C; Totani, T; Tonegawa, M; Okada, H

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Oxford University Press
• Journal: Publications of the Astronomical Society of Japan
• Volume: 68
• Issue: 3
• Article number: 38
• Publication date: 2016-04-26
• Acceptance date: 2016-03-01
• DOI: 10.1093/pasj/psw029
• EISSN: 2053-051X
• ISSN: 0004-6264
• Keywords: cosmology: observations; cosmology: large-scale structure of universe; cosmological parameters; methods: data analysis; galaxies: distances and redshifts