The growth of the disk galaxy UGC8802

TL;DR

This study models the growth of galaxy UGC8802 using a chemical evolution framework, demonstrating that gas inflow timing and inside-out formation explain its high gas content and metallicity gradient.

Contribution

It introduces a simple chemical evolution model with a key infall-peak parameter to reproduce UGC8802's observed properties.

Findings

Late infall-peak time explains high neutral gas content.

Inside-out formation reproduces steep metallicity gradient.

Model successfully matches observed galaxy features.

Abstract

The disk galaxy UGC8802 has high neutral gas content and a flat profile of star formation rate compared to other disk galaxies with similar stellar mass. It also shows a steep metallicity gradient. We construct a chemical evolution model to explore its growth history by assuming its disk grows gradually from continuous gas infall, which is shaped by a free parameter -- the infall-peak time. By adopting the recently observed molecular surface density related star formation law, we show that a late infall-peak time can naturally explain the observed high neutral gas content, while an inside-out disk formation scenario can fairly reproduce the steep oxygen abundance gradient. Our results show that most of the observed features of UGC8802 can be well reproduced by simply `turning the knob' on gas inflow with one single parameter, which implies that the observed properties of gas-rich galaxies could also be modelled in a similar way.