FRANZ: Framework for analytical one-zone blast-wave dynamics

Supernova remnants (SNRs) and super bubbles (SBs) evolve in complex galactic environments shaped by various different processes. While classical modeling approaches successfully describe blast waves in uniform media, a unified framework capable of treating these environmental effects simultaneously is lacking. We aim to develop a flexible analytical framework for modeling blast-wave evolution in arbitrary environments and use it to investigate how large-scale galactic structure affects the dynamics and morphology of evolved SNRs and SBs. We introduce FRANZ (FRamework for ANalytical one-Zone blast-wave dynamics), a modular thin-shell model that follows the local evolution of a shock-surface segment in environments characterized by arbitrary density, velocity and gravitational fields. After validating the model against well-established analytical results, we applied it to study the effects of vertical stratification, galactic shear, and dense galactic substructures on blast-wave evolution. FRANZ reproduces the classical evolution of blast waves in uniform media while extending to complex environments. We derive criteria for disk break out in stratified media, characterize the timescales on which differential rotation deforms blast waves, and identify a new mechanism, that can suppress the momentum coupling in continuously driven blast waves. Interactions with dense filaments modify both shock-surface morphology and dynamics and confound the interpretation of the expansion history of observed remnants, which depends on the density distribution prior to the onset of explosions; the latter is fundamentally inaccessible from the observed state. In highly structured media with a high diffuse-gas volume-filling factor, ages inferred from the observed state may be systematically overestimated. FRANZ provides a computationally inexpensive and extensible framework for studying blast waves in realistic galactic environments. It offers a useful complement to numerical simulations for interpreting observations of evolved SNRs and SBs and for developing improved models of stellar feedback in large-scale simulations.