Exploring AGN - starburst coexistence in galaxies at z$\sim$ 0.8 by the [OIII]4959+5007/[OIII]4363 line ratio

TL;DR

This study models galaxy spectra at z~0.8 to investigate the coexistence of AGN and starburst activity, revealing diverse ionization sources and chemical abundances.

Contribution

It introduces detailed composite models combining shock and photoionization to analyze galaxy spectra, highlighting the coexistence of AGN and starburst phenomena.

Findings

Starburst models fit most spectra within errors.

Approximately half of the spectra are explained by AGN activity.

Some galaxies exhibit multiple ionization sources, including dual AGN.

Abstract

We analyze by detailed modelling the spectra observed from the sample galaxies at z$\sim$0.8 presented by Ly et al (2015), constraining the models by the [OIII]5007+4959/[OIII]4363 line ratios. Composite models accounting for shock and photoionization by AGN or starburst are adopted. O/H are about solar for all the objects, except for a few AGN clouds with O/H= 0.3 -0.5 solar. Starburst models reproduce most of the data within the observational errors. About half of the object spectra are well fitted by an accreting AGN. Some galaxies show multiple radiation sources, such as starburst+AGN, or a double AGN.