Abstract
ABSTRACT The nature of dark energy can be probed by the derivative at redshift z = 0 of the deceleration parameter q(z). It is probably static if or dynamic if , supporting ΛCDM or , respectively, where H denotes the Hubble parameter. We derive , enabling a determination of q(z) by measuring Milgrom’s parameter, , in galaxy rotation curves, equivalent to the coefficient A in the Tully–Fisher relation between a rotation velocity V c and a baryonic mass M b . We infer that dark matter should be extremely light, with clustering limited to the size of galaxy clusters. The associated transition radius to non-Newtonian gravity can conceivably be probed in a freefall Cavendish-type experiment in space.
Highlights
Large scale cosmology is to leading order described by a Friedmann-Robertson-Walker line-element ds2 = −dt2 + a(t)2 dx2 + dy2 + dz2 (1)
The value ΩΛ ≃ 0.7 suggests that our cosmology is presently approaching a de Sitter state with a cosmological horizon at the Hubble radius R = c/H0
In unitary holography of matter, conformal factors encoding positions and gravitation attraction have a hidden low energy scale (6), that introduces a finite sensitivity to low energy scales in the cosmological background (1) parameterized by (H, q). This sensitivity is manifest in a transition to non-Newtonian gravitational attraction, that scales with inverse distance beyond a critical radius rt at accelerations on the scale of the surface gravity of the cosmological horizon
Summary
Gravitational attraction beyond what is inferred from (luminous) baryonic matter is generally observed in galaxies and galaxy clusters (Famae & McGaugh 2012) at accelerations of 1 ̊A s−2 or less This apparent non-Newtonian behavior is commonly attributed to dark matter, based on the success of Newton’s theory of gravity in the solar system and its extension to strong gravity by embedding in general relativity. Supporting data for the latter derive from orbital motions at accelerations a = Rg(c/r)2 ≃ 10−6 − 10−2 m s−2 of planets in the solar system at distances r, where Rg = GM⊙/c2 ≃ 1.5 km denotes the gravitational radius of the Sun with Newton’s constant G. Data are from galaxy curves with essentially zero redshifts from Famae & McGaugh (2012)
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