Do the constants of nature couple to strong gravitational fields?

TL;DR

This paper investigates whether fundamental constants like the fine structure constant vary in strong gravitational fields by re-analyzing white dwarf spectra with improved atomic data.

Contribution

It provides a re-evaluation of previous measurements of alpha variation in white dwarf spectra using a high S/N reference spectrum for calibration.

Findings

Refined atomic data calibration reduces systematic uncertainties.

Revised constraints on alpha variation in strong gravitational fields.

Highlights importance of accurate atomic data in fundamental physics tests.

Abstract

Recently, white dwarf stars have found a new use in the fundamental physics community. Many prospective theories of the fundamental interactions of Nature allow traditional constants, like the fine structure constant $\alpha$, to vary in some way. A study by Berengut et al. (2013) used the Fe/Ni V line measurements made by Preval et al. (2013) from the hot DA white dwarf G191-B2B, in an attempt to detect any variation in $\alpha$. It was found that the Fe V lines indicated an increasing alpha, whereas the Ni V lines indicated a decreasing alpha. Possible explanations for this could be misidentification of the lines, inaccurate atomic data, or wavelength dependent distortion in the spectrum. We examine the first two cases by using a high S/N reference spectrum from the hot sdO BD+28$^{\circ}$4211 to calibrate the Fe/Ni V atomic data. With this new data, we re-evaluate the work of Berengut et al. (2013) to derive a new constraint on the variation of alpha in a gravitational field.