Measurement of peculiar velocities by combining redshifts and distance indicators is a powerful way to measure the growth rate of a cosmic structure and test theories of gravity at low redshift. Here we constrain the growth rate of the structure by comparing observed Fundamental Plane peculiar velocities for 15 894 galaxies from the 6dF Galaxy Survey (6dFGS) and Sloan Digital Sky Survey (SDSS) with predicted velocities and densities from the 2M++ redshift survey. We measure the velocity scale parameter β≡Ωγm/b=0.372+0.034−0.050β≡Ωmγ/b=0.372−0.050+0.034 and 0.314+0.031−0.0470.314−0.047+0.031 for 6dFGS and SDSS, respectively, where Ωm is the mass density parameter, γ is the growth index, and b is the bias parameter normalized to the characteristic luminosity of galaxies, L*. Combining 6dFGS and SDSS, we obtain β = 0.341 ± 0.024, implying that the amplitude of the product of the growth rate and the mass fluctuation amplitude is fσ8 = 0.338 ± 0.027 at an effective redshift z = 0.035. Adopting Ωm = 0.315 ± 0.007, as favoured by Planck and using γ = 6/11 for General Relativity and γ = 11/16 for DGP gravity, we get S8(z=0)=σ8Ωm/0.3−−−−−−√=0.637±0.054S8(z=0)=σ8Ωm/0.3=0.637±0.054 and 0.741 ± 0.062 for GR and DGP, respectively. This measurement agrees with other low-redshift probes of large-scale structure but deviates by more than 3σ from the latest Planck CMB measurement. Our results favour values of the growth index γ > 6/11 or a Hubble constant H0 > 70 km s−1 Mpc−1 or a fluctuation amplitude σ8 < 0.8 or some combination of these. Imminent redshift surveys such as Taipan, DESI, WALLABY, and SKA1-MID will help to resolve this tension by measuring the growth rate of cosmic structure to 1 per cent in the redshift range 0 < z < 1.

中文翻译：

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6dFGS和SDSS特异速度联合分析宇宙结构生长速率及重力测试

通过结合红移和距离指标来测量特殊速度是测量宇宙结构增长率和测试低红移引力理论的有力方法。在这里，我们通过比较来自 6dF 星系调查 (6dFGS) 和斯隆数字巡天 (SDSS) 的 15 894 个星系的观测基面特殊速度与来自 2M++ 红移调查的预测速度和密度来限制结构的增长速度。我们测量速度标度参数 β≡Ωγm/b=0.372+0.034−0.050β≡Ωmγ/b=0.372−0.050+0.034 和 0.314+0.031−0.0470.314−0.047+0.034，其中 SS 分别为 SS，Ω 和 0.047+0.031质量密度参数，γ 是生长指数，b 是归一化为星系特征光度 L* 的偏差参数。结合 6dFGS 和 SDSS，我们得到 β = 0.341 ± 0.024，这意味着在有效红移 z = 0.035 时，增长率和质量波动幅度的乘积幅度为 fσ8 = 0.338 ± 0.027。采用普朗克赞成的Ωm = 0.315 ± 0.007，广义相对论采用γ = 6/11，DGP引力采用γ = 11/16，我们得到S8(z=0)=σ8Ωm/0.3−−−−−−√ =0.637±0.054S8(z=0)=σ8Ωm/0.3=0.637±0.054 和 0.741±0.062 对于 GR 和 DGP，分别。该测量与其他大尺度结构的低红移探测器一致，但与最新的普朗克 CMB 测量偏差超过 3σ。我们的结果有利于增长指数 γ > 6/11 或哈勃常数 H0 > 70 km s-1 Mpc-1 或波动幅度 σ8 < 0.8 或这些的某种组合的值。即将进行的红移巡天，例如 Taipan、DESI、WALLABY、