Accelerated cosmological expansion without tension in the Hubble parameter^*

Fast evolution of the Hubble parameter H(z)

614 Yeongsil-Gwan, Department of Physics and Astronomy, Sejong University, 143-747 Seoul, South Korea

^** e-mail: mvp@sejong.ac.kr

Published online: 9 January 2018

Abstract

The H₀-tension problem poses a confrontation of dark energy driving latetime cosmological expansion measured by the Hubble parameter H(z) over an extended range of redshifts z. Distinct values H₀ ≃ 73 km s^–1 Mpcs^–1 and H₀ ≃ 68 km s^–1 Mpcs^–1 obtain from surveys of the Local Universe and, respectively, ΛCBM analysis of the CMB. These are representative of accelerated expansion with H′(0) ≃ 0 by and, respectively, H′(0) > 0 in ΛCDM, where is a fundamental frequency of the cosmological horizon in a Friedmann-Robertson-Walker universe with deceleration parameter q(z) = -1 + (1+z)H^–1 H′(z). Explicit solution H(z) = H₀ and, respectively, H(z) = H₀ are here compared with recent data on H(z) over 0 ≲ z ≲ 2.The first is found to be free of tension with H₀ from local surveys, while the latter is disfavored at 2:7σ A further confrontation obtains in galaxy dynamics by a finite sensitivity of inertia to background cosmology in weak gravity, putting an upper bound of m ≲ 10^–30 eV on the mass of dark matter. A C⁰ onset to weak gravity at the de Sitter scale of acceleration a_dS = cH(z), where c denotes the velocity of light, can be seen in galaxy rotation curves covering 0 ≲ z ≲ 2 Weak gravity in galaxy dynamics hereby provides a proxy for cosmological evolution.