Modelling Starbursts in HII Galaxies: What do we need to fit the observations?

TL;DR

This paper presents a comprehensive modeling approach combining chemical evolution, stellar population synthesis, and photoionization to reproduce observed spectra and properties of HII galaxies, emphasizing the importance of star formation history and metallicity evolution.

Contribution

It introduces a self-consistent modeling framework that integrates multiple codes to accurately simulate HII galaxy spectra and their observable properties.

Findings

Models reproduce observed spectra and emission line diagnostics.

Star formation history and metallicity evolution are key to matching observations.

The approach successfully explains spectral and chemical properties of local HII galaxies.

Abstract

We have computed a series of realistic and self-consistent models that have been shown to be able to reproduce the emitted spectra of HII galaxies in a star bursting scenario (Martin-Majon et al. 2008). Our models combine different codes of chemical evolution, evolutionary population synthesis and photoionization. The emitted spectrum of HII galaxies is reproduced by means of the photoionization code CLOUDY (Ferland, 1998), using as ionizing spectrum the spectral energy distribution (SED) of the modelled HII galaxy, calculated using the new and updated stellar population models PopStar (Molla & Garcia-Vargas 2009, in prep.).This, in turn, is calculated according to a star formation history and a metallicity evolution given by a chemical evolution model. Each model is characterized by three parameters which are going to determine the evolution of the modeled galaxy: an initial efficiency of star formation, the way in which burst take place, and the time of separation between these bursts. Some model results emerging from the combination of different values for these three parameters are shown here. Our technique reproduces observed abundances, diagnostic diagrams and equivalent width-colour relations for local HII galaxies.