Radiation Transfer Modeling of UV light through Outflows in Local Star-Forming Galaxies
Massive outflows are an important component of a galaxy's evolution, regulating star formation and affecting the dynamics of the surrounding media. Extracting outflow information from absorption spectra is difficult, but radiation transfer modeling offers an insight into these processes. As such, we analyze the signatures of galactic outflows in the ultraviolet spectra of local star-forming galaxies in the CLASSY survey using a semi-analytical line transfer model. We focus on the resonant lines of several ionization states of silicon that trace cool and warm gas, in order to study the geometric and physical characteristics of the outflowing gas. From the model constraints, we estimate the mass outflow rates for these galaxies and look for trends with other galactic properties. We compare our estimated relationships with those in previously established literature, and speculate about reasons for similarities and deviations between this work and others. In addition, we derive momentum and energy outflow rates. We find that our semi-analytical method captures the same trends as Gaussian fitting techniques with regard to outflow rates; however the magnitude of these values often differs. Our work also reiterates the positive correlation between the mass outflow rates and star-formation rates. These results also suggest that the analyzed star-forming galaxies host momentum driven outflows, as opposed to energy driven outflows.