The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: testing gravity with redshift space distortions using the power spectrum multipoles

Abstract

We analyse the anisotropic clustering of the Baryon Oscillation Spectroscopic\nSurvey (BOSS) CMASS Data Release 11 (DR11) sample, which consists of $690\\,827$\ngalaxies in the redshift range $0.43 < z < 0.7$ and has a sky coverage of\n$8\\,498\\,\\text{deg}^2$. We perform our analysis in Fourier space using a power\nspectrum estimator suggested by Yamamoto et al. (2006). We measure the\nmultipole power spectra in a self-consistent manner for the first time in the\nsense that we provide a proper way to treat the survey window function and the\nintegral constraint, without the commonly used assumption of an isotropic power\nspectrum and without the need to split the survey into sub-regions. The main\ncosmological signals exploited in our analysis are the Baryon Acoustic\nOscillations and the signal of redshift space distortions, both of which are\ndistorted by the Alcock-Paczynski effect. Together, these signals allow us to\nconstrain the distance ratio $D_V(z_{\\rm eff})/r_s(z_d) = 13.89\\pm 0.18$, the\nAlcock-Paczynski parameter $F_{\\rm AP}(z_{\\rm eff}) = 0.679\\pm0.031$ and the\ngrowth rate of structure $f(z_{\\rm eff})\\sigma_8(z_{\\rm eff}) = 0.419\\pm0.044$\nat the effective redshift $z_{\\rm eff}=0.57$. We did not find significant\nsystematic uncertainties for $D_V/r_s$ or $F_{\\rm AP}$ but include a systematic\nerror for $f\\sigma_8$ of $3.1\\%$. Combining our dataset with Planck to test\nGeneral Relativity (GR) through the simple $\\gamma$-parameterisation, reveals a\n$\\sim 2\\sigma$ tension between the data and the prediction by GR. The tension\nbetween our result and GR can be traced back to a tension in the clustering\namplitude $\\sigma_8$ between CMASS and Planck.\n