Galaxy dynamics tracing quantum cosmology beyond ΛCDM below the de Sitter scale of acceleration

In disks of spiral galaxies, the baryonic Tully-Fisher relation (bTFR) shows a discrepancy α > aN between observed orbital acceleration α and expected Newtonian acceleration aN based on baryonic matter and Newton's law of gravitation. We consider sensitivity of weak gravitation in galaxy dynamics to the de Sitter scale of acceleration adS=cH of the background cosmology, given by the velocity of light c and the Hubble parameter H. The onset to bTFR is identified with crossing of the Rindler horizon and Hubble horizon at accelerations adS, giving rise to a sharp essentially C0-transition to anomalous dynamics α > aN across ζ=1, where ζ=aN/adS. This C0-transition is observed at 6σ significance in SPARC. The anomalous dynamics derives from reduced inertia (a symmetry of the Hamiltonian of orbital motion) due to a Hubble cut-off of potential energy in the Rindler frame of the orbiting stars. Equivalently, this reduced inertia is identified with a dimensional reduction in the Green's function of the Laplace operator. The bTFR is shown to be parameterized by a Milgrom parameter a0=c2/(2π) \sqrt{J}, where J is the trace of the Schouten tensor. This interpretation unifies, with no free parameters, the short time scales in galaxy dynamics and accelerated galaxy formation at cosmic dawn ('JWST Impossible galaxies'). By this sensitivity, spiral galaxies can be used as tracers of background cosmology, providing novel ways to measure the Hubble parameter H0 by resolving the location of the C0-transition at ζ=1. Combined with a0, the resulting H0 carries an associated deceleration parameter q0 through J=(1-q)H^2.