2017ApJ...848...28V

Galaxy dynamics probe weak gravity at accelerations below the de Sitter scale of acceleration a_dS=cH, where c is the velocity of light and H is the Hubble parameter. Low- and high-redshift galaxies hereby offer a novel probe of weak gravity in an evolving cosmology, satisfying H(z)=H₀sqrt(1+ω_m(6z+12z²+12z³+6z⁴+(6/5)z⁵))/(1+z) with matter content ω_m=0.2808±0.028 sans tension to H₀ in surveys of the local universe. Galaxy rotation curves show anomalous galaxy dynamics in weak gravity a_N a_dS across a transition radius r_t=4.7 kpc M₁₁^1/2(H₀/H)¹² in galaxies of mass M=10¹¹ M_☉M₁₁, where a_N is the Newtonian acceleration based on baryonic matter content. We identify this behavior with a holographic origin of inertia from entanglement entropy, which introduces a C⁰ onset across a_N=a_dS with asymptotic behavior described by a Milgrom parameter satisfying a₀=ω₀/2π, where ω₀=sqrt(1-q)H is a fundamental eigenfrequency of the cosmological horizon. Extending an earlier confrontation with data covering 0.003 a_N/a_dS 1 at redshift z∼0 in Lellie et al., the modest anomalous behavior in the Genzel et al. sample at redshifts 0.854 z 2.282 is found to be mostly due to clustering 0.36 a_N/a_dS 1 close to the C⁰ onset to weak gravity and an increase of up to 65% in a₀.