Measuring chemical evolution and gravitational dependence ofαusing ultraviolet Fe v and Ni v transitions in white-dwarf spectra

Abstract

In this paper, we present the details of the ab initio high-precision configuration interaction and many-body perturbation theory calculations that were used by Berengut et al. [Phys. Rev. Lett. 111, 010801 (2013)] to place limits on the dependence of the fine-structure constant, $\ensuremath{\alpha}$, on the gravitational field of the white-dwarf star G191-B2B. These calculations were combined with laboratory wavelengths and spectra from the Hubble Space Telescope Imaging Spectrograph to obtain the result $\ensuremath{\Delta}\ensuremath{\alpha}/\ensuremath{\alpha}=(4.2\ifmmode\pm\else\textpm\fi{}1.6)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ and $(\ensuremath{-}6.1\ifmmode\pm\else\textpm\fi{}5.8)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ using Fe v and Ni v transitions, respectively. The uncertainty in these results are dominated by the uncertainty in the laboratory wavelengths. In this work we also present ab initio calculations of the isotopic shifts of the Fe v transitions. We show that improved laboratory spectra will enable determination of the relative isotope abundances in Fe v to an accuracy of $\ensuremath{\sim}$20%. Therefore this work provides a strong motivation for new laboratory measurements.