An analytical galactic chemical evolution model with gas inflow and a terminal wind

Abstract

We present a new analytical galactic chemical evolution (GCE) model with gas inflow, internally caused outflow, and extra gas loss after a period of time. The latter mimics the ram pressure stripping of a dwarf satellite galaxy near the pericenter of its orbit around a host galaxy. The new model is called Inflow with Ram Pressure Stripping (IRPS). We fit the $\alpha$-element ([$\alpha$/H]) distributions of the Draco, Sculptor, Fornax, Leo II, Leo I, and And XVIII dwarf spheroidal galaxies. We compared the best fits of IRPS with four other GCE models. The IRPS fits half of the galaxies in our set better than the Leaky Box, Pre-enriched, Accretion, and Ram Pressure Stripping models. Unlike previous models, none of the IRPS model parameters -- not even the effective yield -- correlates with galaxy properties, like luminosity. One of the IRPS parameters is the $\alpha$-abundance at which stripping began. That parameter can override the effective yield in determining the galaxy's mean $\alpha$-abundance.