The Linear Growth of Structure in the R_h=ct Universe

TL;DR

This study compares the R_h=ct cosmology with LCDM using growth rate data, finding that R_h=ct aligns better with observations at certain redshifts, highlighting the need for more precise measurements.

Contribution

It provides an empirical test of the R_h=ct model against LCDM using recent growth rate measurements, emphasizing differences in predicted structure growth.

Findings

R_h=ct fits the data better for 0<z<1

LCDM and R_h=ct are indistinguishable when LCDM is optimized

Low-redshift measurements suggest lower fluctuation amplitude in LCDM

Abstract

We use recently published redshift space distortion measurements of the cosmological growth rate, f sigma_8(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 LCDM 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 f sigma_8(z) predicted by the standard model---but not by R_h=ct---is absent in the data. When LCDM 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 LCDM. Our results strongly affirm the need for more precise measurements of f sigma_8(z) at all redshifts, but especially at z < 1.