2023ApJ...948...96C

We present a sample of 330 blue edge-on low surface brightness galaxies (ELSBGs). To understand the chemical evolution of ELSBGs, we derived the gas-phase abundance and the [α/Fe] ratio. Compared with star-forming galaxies, ELSBGs show a flatter trend in the mass-metallicity (M_*-Z) relation, which suggests that the oxygen abundance enhancement is inefficient. We focused on 77 ELSBGs with H I data and found that the closed-box model cannot explain their gas fraction and metallicity relation, which implies that infall and/or outflow is needed. We derived the [α/Fe] ratio of normal ELSBG (<10^9.5M_⊙) and massive ELSBG (> = 10^9.5M_⊙) using single stellar population grids from the MILES stellar library. The mean [α/Fe] ratios are 0.18 and 0.4 for normal ELSBG and massive ELSBG, respectively. We suggest that the long timescales of star formation and/or metal-rich gas outflow events caused by SNe Ia winds are likely to be responsible for the α-enhancement of massive ELSBGs.