The linear growth of structure in the R_h = ct universe

We use recently published redshift space distortion measurements of the cosmological growth rate, fσ₈(z), to examine whether the linear evolution of perturbations in the R_h = ct cosmology is consistent with the observed development of large-scale structure. We find that these observations favour R_h = ct over the version of Λ cold dark matter (ΛCDM) optimized with the joint analysis of Planck and linear growth rate data, particularly in the redshift range 0 < z < 1, where a significant curvature in the functional form of fσ₈(z) predicted by the standard model-but not by R_h = ct-is absent in the data. When ΛCDM is optimized using solely the growth rate measurements; however, the two models fit the observations equally well though, in this case, the low-redshift measurements find a lower value for the fluctuation amplitude than is expected in Planck ΛCDM. Our results strongly affirm the need for more precise measurements of fσ₈(z) at all redshifts, but especially at z < 1.