Constraining spacetime variations of nuclear decay rates from light curves of type Ia supernovae

Abstract

The luminosity of fading type Ia supernovae is governed by radioactive decays of $^{56}\mathrm{Ni}$ and $^{56}\mathrm{Co}$. The decay rates are proportional to the Fermi coupling constant ${G}_{\mathrm{F}}$ and, therefore, are determined by the vacuum expectation value $v$ of the Brout-Englert-Higgs field. We use publicly available sets of light curves of type Ia supernova at various redshifts to constrain possible spacetime variations of the $^{56}\mathrm{Ni}$ decay rate. The resulting constraint is not very tight; however, it is the only direct bound on the variation of the decay rate for redshifts up to $z\ensuremath{\sim}1$. We discuss potential applications of the result to searches for nonconstancy of ${G}_{\mathrm{F}}$ and $v$.