A finite-temperature constitutive extension of the classical Type Ia supernova model

Abstract We develop a finite-temperature constitutive extension of the classical Type Ia supernova model by treating the vacuum, in analogy with optical media, as a constitutive electromagnetic medium whose permittivity depends on the surrounding supernova plasma temperature. The constitutive modification becomes operative above the critical temperature at which thermal electron–positron pair production renders finite-temperature corrections to the electromagnetic propagator significant, yielding finite-temperature extensions of the photon-diffusion equation and the analytical Arnett light-curve solution. The resulting framework predicts constitutive corrections to the inferred peak luminosity, synthesized 56Ni mass, absolute magnitude, luminosity distance, and light-curve morphology, while leaving the total radiated electromagnetic energy unchanged. Within this framework, the observed luminosity of a Type Ia supernova is determined jointly by the radioactive energy released in the explosion and by the constitutive state governing electromagnetic propagation, implying that the classical standard-candle paradigm is no longer complete. Applying the constitutive formalism to observed Type Ia supernovae, we reconstruct the supernova plasma temperature and independently recover the luminosity–distance relation previously derived within an independent constitutive cosmological framework. The convergence of these independent formalisms provides a non-trivial internal consistency result and identifies a possible connection with the Hubble tension: the constitutive correction acts directly on the supernova-based distance scale, while photon decoupling occurs far below the critical temperature, in the constant-c regime.