White Dwarf Spectra for Studies of Time Variation of the Fine Structure Constant

Abstract

We report a newly updated constraint on space-time variation in the fine structure constant, α ¼ e 2 4πε 0 ℏc , from an analysis of white dwarf spectra. We obtain Δα/α = (0.007 ± 0.087) × 10 −6 from a comparison of laboratory spectra of Fe V with those found in the spectra from the white dwarf G191-B2B. The obtained result in this study is used to suggest further improvement in observational technique which would lead to a tighter constraint on Δα/α.

Updated Constraints on the Variations of the Fine-Structure Constant from an Analysis of White-Dwarf Spectra

“…, where φ = GM rc 2 , M is the mass of the white dwarf/Earth, r is the radius of the white dwarf/Earth, α 0 is the laboratory-derived value of the fine-structure constant, and k α is a sensitivity parameter. Therefore, hot white-dwarf stars may be ideal probes to investigate the relationship between ∆α/α and strong gravitational fields (e.g., [38,39]):…”

“…A new method has been proposed for the analysis of the optical spectra of quasars and white-dwarf stars, and has been applied to search for spatial and temporal variability of the fine-structure constant. Using this technique, recent studies [38,39] determined a change over cosmological time of ∆α/α = (0.007 ± 0.087) × 10 −6 from a comparison of laboratory spectra of [Fe V] with the spectra of the white-dwarf star G191-B2B with a gravitational redshift z = ∆φ ≈ 5 × 10 −5 . This new approach allows the estimation of values of ∆α/α in the early stages of the Universe's evolution from the spectra of white-dwarf stars, and has the advantage of being much more transparent and less subject to systematics than previous methods.…”

Constraining the secular variation of the gravitational constant using white-dwarf stars spectra

“…The spectrum of white-dwarf star G191-B2B included several interesting absorptions. This white-dwarf star is usually sensitive to ∆α/ α due to the [Fe V] and [Ni V] transitions, as we have indicated in the previous works [29][30][31][32][33][34][35][36][37][38]. From comparisons of different [Fe V] lines, one can obtain measurements of several fundamental constants such as the fine-structure constant, the proton-to-electron mass ratio and the gravitational constant.…”

“…From comparisons of different [Fe V] lines, one can obtain measurements of several fundamental constants such as the fine-structure constant, the proton-to-electron mass ratio and the gravitational constant. Our study used the same procedure of analysis with non-linear least-squares methods [29][30][31][32][33][34][35][36][37][38]. Using simultaneously ofminimizing with all free parameters including column density , the absorption redshift , the Doppler, and line width , we estimated ̇ ⁄ and it associated with the error in each observed line of [Fe V].…”

“…The linked space-time variation between α and would be related by ̇ ∼ ̇ ⁄ ⁄ based on the model-dependent. Current studies used high-resolution of astrophysical observations to improve the most stringent limits on this variation, for example, ∆α/ α = ( 0.007 ± 0.087) × 10 for the fine-structure constant and ∆µ/ µ = ( 0.025 ± 0.262) × 10 for the proton-to-electron mass ratio [29][30][31].…”