Episodic Model For Star Formation History and Chemical Abundances in Giant and Dwarf Galaxies

TL;DR

This paper presents a unified model for galaxy evolution that combines gas inflow, outflow, and oscillatory star formation to explain observed chemical abundances in both giant and dwarf galaxies.

Contribution

It introduces an oscillatory star formation model linked to interstellar medium phases, explaining metallicity variations across galaxy types.

Findings

Oscillatory star formation periods range from 1 to 30 million years.

Metallicity evolution depends on outflow and evaporation processes.

Different outflow and evaporation rates reproduce observed abundances in giant and dwarf galaxies.

Abstract

In search for a synthetic understanding, a scenario for the evolution of the star formation rate and the chemical abundances in galaxies is proposed, combining gas infall from galactic halos, outflow of gas by supernova explosions, and an oscillatory star formation process. The oscillatory star formation model is a consequence of the modelling of the fractional masses changes of the hot, warm and cold components of the interstellar medium. The observed periods of oscillation vary in the range $(0.1-3.0)\times10^{7}$\,yr depending on various parameters existing from giant to dwarf galaxies. The evolution of metallicity varies in giant and dwarf galaxies and depends on the outflow process. Observed abundances in dwarf galaxies can be reproduced under fast outflow together with slow evaporation of cold gases into hot gas whereas slow outflow and fast evaporation is preferred for giant galaxies. The variation of metallicities in dwarf galaxies supports the fact that low rate of SNII production in dwarf galaxies is responsible for variation in metallicity in dwarf galaxies of similar masses as suggested by various authors.