Fine-structure constant constraints on late-time dark energy transitions

Abstract

We use recent astrophysical and local tests of the stability of the fine-structure constant, α, to constrain a particular phenomenological but physically motivated class of models in which the dark energy equation of state can undergo a rapid transition at low redshifts, perhaps associated with the onset of the acceleration phase. We set constraints on the phenomenological parameters describing such possible transitions, in particular improving previous constraints (which used only cosmological data) on the present-day value of the dark energy equation of state in these models. We specifically quantify how these constraints are improved by the addition of the α measurements. We find no evidence for a transition associated with the onset of acceleration. In this model the α measurements lead to a bound on Weak Equivalence Principle violations of η < 4×10 −15 (at 68.3% confidence level), improving on the recent MICROSCOPE bound by about a factor of three.

MICROSCOPE’s view at gravitation

“…Note that although this review is limited to gravity models that have been central to MICROSCOPE investigations and data analysis (a fifth force behaving as a Yukawa interaction, a dilaton-like field that can act as an ultra-light bosonic dark matter candidate, a chameleon field and a U(1) boson), the enlarged scientific community has already benefited from MICROSCOPE, e.g. in the search for vector dark matter [162,163], including a dark photon [164][165][166], for relic neutrinos [167], and in constraining dark energy models (such as Bekenstein models [168], dynamical dark energy [169,170] or dark forces [171], for which local tests are complementary to cosmology and astrophysics observations), string theory [172][173][174], topological defects [175,176], and the possibility that the muon g − 2 anomaly arises from the existence of a new field [177]. The wealth of those analyses shows the powerful versatility of testing the WEP with ever increasing precision.…”

Newtonian-like gravity with variable G

“…The search for tiny variations of physical constants is a very active field and some attempts include Refs. [12][13][14][15][16][17][18] Essentially, all proposals of a varying G coupling are formulated within the relativistic/covariant context. There is no consistent Newtonian theory admitting a arXiv:2009.04434v2 [gr-qc] 11 Sep 2020 varying G. The reason for that lies essentially on the non-trivial definition of energy conservation and issues related to invariance under Galilean transformations.…”