Distinguishing freezing and thawing dark energy models through measurements of the fine-structure constant

Abstract

Mapping the behaviour of dark energy is a pressing task for observational cosmology. Phenomenological classification divides dynamical dark energy models into freezing and thawing, depending on whether the dark energy equation of state is approaching or moving away from w = p/ρ = −1. Moreover, in realistic dynamical dark energy models the dynamical degree of freedom is expected to couple to the electromagnetic sector, leading to variations of the fine-structure constant α. We discuss the feasibility of distinguishing between the freezing and thawing classes of models with current and forthcoming observational facilities and using a parametrisation of the dark energy equation of state, which can have either behaviour, introduced by Mukhanov as fiducial paradigm. We illustrate how freezing and thawing models lead to different redshift dependencies of α, and use a combination of current astrophysical observations and local experiments to constrain this class of models, improving the constraints on the key coupling parameter by more than a factor of two, despite considering a more extended parameter space than the one used in previous studies. We also briefly discuss the improvements expected from future facilities and comment on the practical limitations of this class of parametrisations. In particular, we show that sufficiently sensitive data can distinguish between freezing and thawing models, at least if one assumes that the relevant parameter space does not include phantom dark energy models.

Fundamental physics with ESPRESSO: Constraints on Bekenstein and dark energy models from astrophysical and local probes

“…As an example, it has been previously suggested [46] that sufficiently sensitive α data can distinguish between freezing and thawing models of dark energy, and our analysis of the CPL model is consistent with those findingsfor example, one can notice in the bottom left panel of Fig. 2 that the Archival and Dedicated datasets lead to small differences in the two-dimensional ζ-w a plane constraints.…”

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.…”