Gas and Metal Contents of Galaxies and Gaseous Halos: Preventive versus Ejective Feedback

Understand

Using a semi-analytical approach we investigate the characteristics of predictions for the masses and metallicities of the baryonic matter in and around galaxies made by three galaxy formation models.

• These models represent three different feedback scenarios: one model with purely ejective feedback, one model with ejective feedback with reincorporation of ejected gas, and one preventative model.
• We find that, when the model parameters are adjusted to predict the correct stellar masses for a range of halo masses between 10^{10} to 10^{12}Msun, these three scenarios have very different predictions for the masses and metallicities of the interstellar and circum-galactic media.
• Compared with current observational data, the model implementing preventative feedback has a large freedom to match a broad range of observational data, while the ejective models have difficulties to match a number of observational constraints simultaneously, independent of how the ejection and reincorporation are implemented.