Nonexistence and existence of shock profiles in the Bemfica-Disconzi-Noronha model

This paper studies a four-field hyperbolic PDE model that was recently introduced by Bemfica, Disconzi, and Noronha for the pure radiation fluid with viscosity, asks whether shock waves admit continuous profiles in this description. The containing two free parameters $\ensuremath{\mu}$, $\ensuremath{\nu}$ being causal whenever one chooses $(\ensuremath{\mu},\ensuremath{\nu})$ from certain range $\mathcal{C}\ensuremath{\subset}{\mathbb{R}}^{2}$, shows any choice of interior $\mathcal{C}$, there is dichotomy so far as (i) shocks sufficiently small amplitude (ii) other, thus necessarily nonsmall, do not. finding does not preclude possibility if specific part $\mathcal{S}$ boundary disappears all have profiles; parameter set corresponds to ``sharply causal'' case, which characteristic speeds dissipation operator speed light.