Current and Future White Dwarf Mass-radius Constraints on Varying Fundamental Couplings and Unification Scenarios

TL;DR

This paper explores how white dwarf observations can be used to test variations in fundamental physical constants and unification theories, providing a new astrophysical approach to fundamental physics constraints.

Contribution

It models the effects of varying fundamental couplings on white dwarf mass-radius relations and discusses how future measurements can improve constraints on unification scenarios.

Findings

Current data do not tightly constrain the parameters.

Future Gaia data can improve constraints and break degeneracies.

White dwarf observations can complement laboratory tests of fundamental constants.

Abstract

We discuss the feasibility of using astrophysical observations of white dwarfs as probes of fundamental physics. We quantify the effects of varying fundamental couplings on the white dwarf mass-radius relation in a broad class of unification scenarios, both for the simple case of a polytropic stellar structure model and for more general models. Independent measurements of the mass and radius, together with direct spectroscopic measurements of the fine-structure constant in white dwarf atmospheres lead to constraints on combinations of the two phenomenological parameters describing the underlying unification scenario (one of which is related to the strong sector of the theory while the other is related to the electroweak sector). While currently available measurements do not yet provide stringent constraints, we show that forthcoming improvements, expected for example from the Gaia satellite, can break parameter degeneracies and lead to constraints that ideally complement those obtained from local laboratory tests using atomic clocks.