POSSIBLE QUINTESSENCE-LIKE PSEUDOSCALAR DARK ENERGY EFFECTS ON 56FE NUCLEAR TRANSITION ENERGIES OBSERVED IN SUPERNOVA 1991T

Fitting the background-subtracted spectral data of SN 1991T indicates that the gamma rays emitted by the 56Fe nuclei are shifted to lower energies at the 3.2σ statistical level. The average energy shift of both the first and second excited states is found to be δE/E = 0.023±0.007 where the uncertainty is given at one standard deviation. Assuming this energy shift is constant as the universe evolves over time implies that δ ˙ E/E = (5.2±1.7)×10−10 yr−1. It is assumed that this energy shift is caused by a dynamical pseudoscalar field Q that acts as dark energy with a coupling to the nucleons of atoms. This interaction would cause an apparent variation in the mass of the pion, thereby shifting the gamma ray energies. To relate the energy deviation to the pion mass and Q, the excited 56Fe nucleus is modeled as a deformed rigid rotor and vibrating liquid drop. The implied pion mass variation, indicated by the observed energy deviations, is found to be δ ˙ m/m=−(2.2±0.7)×10−10 yr−1, modeling the nucleus as a deformed rigid rotor, and δ ˙ m/m=−(2.5±0.8)×10−10 yr−1, modeling the nucleus as a vibrating liquid drop. It can also be used to determine the value of ˙ Q, which corresponds to the term of the dark energy field that changes as the universe evolves. This quantity will depend on the free parameters α and p, which are the decay constant coefficient of the field and the power of the quintessence tracking potential, respectively. The maximum value of ˙ Q will result for α = 0.1 and p = 1. These values are ˙ Q = (1.07±0.35)×108 GeV/yr for the nucleus as a rigid rotor and ˙ Q = (1.22 ± 0.39) × 108 GeV/yr for the nucleus as a vibrating liquid drop. The measured values of the dark energy equation of state parameter determined by DESI observations of the BAO and complemented by Planck observations of the CMB and SNe indicate that there exists an allowed α–p parameter space. This implies that the fractional kinetic energy densities determined by ˙ Q are consistent with cosmological observations under the assumptions that are used throughout this work. Here upper limits are also presented to take into account the possibility that the observed energy deviations are caused by an unknown systematic error.