The Chemical Evolution of LSB Galaxies

TL;DR

This study analyzes the chemical composition of low surface brightness galaxies, using SDSS data and extensive modeling, to understand their stellar populations, chemical evolution, and star formation history.

Contribution

It provides the first detailed chemical abundance analysis of LSB galaxies and tests various chemical evolution models to constrain their stellar populations and star formation rates.

Findings

LSB galaxies do not have bottom-heavy IMFs.

LSB galaxies have similar ages to high surface brightness galaxies.

Star formation rates in LSB galaxies are significantly lower.

Abstract

We have derived oxygen and nitrogen abundances of a sample of late-type, low surface brightness (LSB) galaxies found in the Sloan Digital Sky Survey (SDSS). Furthermore, we have computed a large grid (5000 models) of chemical evolution models (CEMs) testing various time-scales for infall, baryon densities and several power-law initial mass functions (IMFs) as well. Because of the rather stable N/O-trends found both in CEMs (for a given IMF) and in observations, we find that the hypotheses that LSB galaxies have stellar populations dominated by low-mass stars, i.e., very bottom-heavy IMFs (see Lee et al. 2004), can be ruled out. Such models predict much too high N/O-ratios and generally too low O/H-ratios. We also conclude that LSB galaxies probably have the same ages as their high surface brightness counterparts, although the global rate of star formation must be considerably lower in these galaxies.