Transonic galactic wind model including stellar feedbacks and application to outflows in high/low-z galaxies.

This article presents a transonic galactic wind model that extends Parker’s solar wind theory by incorporating the gravitational potentials of both dark matter halos and stellar components, along with distributed mass and energy injections from supernova feedback under spherically symmetric and steady assumptions. The model classifies possible transonic solutions and applies them to observed outflow velocities in star-forming galaxies to estimate mass fluxes and mass loading rates—the ratio of mass flux to star formation rate (SFR). Results indicate that the mass loading rate inversely correlates with galaxy mass and SFR: less massive galaxies (stellar mass ∼10⁷–10⁸ M☉) exhibit mass loading rates exceeding unity, implying effective ejection of interstellar medium (ISM) into intergalactic space, whereas massive galaxies (stellar mass ∼10¹⁰–10¹¹ M☉) have rates below unity, indicating inefficient ISM ejection due to stronger gravitational potential. Comparisons with the commonly used shell model reveal that this transonic model provides more consistent mass flux estimates by explicitly including gravitational effects and flow profiles, and its predictions align reasonably with numerical galaxy formation studies, though discrepancies remain at high redshifts. The study also discusses the model’s assumptions, applicability, and implications for galaxy evolution and intergalactic medium enrichment.