# An $\rm H\alpha$ Imaging Survey of the Low Surface Brightness Galaxies Selected from the Spring Sky Region of the 40% ALFALFA HI Survey

## TL;DR

This study conducts an H-alpha imaging survey of 357 low surface brightness galaxies from the ALFALFA HI survey, revealing their star formation properties and deviations from the Kennicutt-Schmidt law, but adherence to the extended Schmidt law.

## Contribution

First comprehensive H-alpha imaging survey of LSBGs from ALFALFA, analyzing their star formation rates and relation to gas and stellar mass.

## Key findings

- LSBGs have similar HI surface density to normal galaxies.
- LSBGs exhibit much lower SFRs and star formation surface density.
- They deviate from the Kennicutt-Schmidt law but follow the extended Schmidt law.

## Abstract

We present a narrow $\rm H\alpha$-band imaging survey of 357 low surface brightness galaxies (LSBGs) that are selected from the spring sky region of the 40% Arecibo Legacy Fast Arecibo L-band Feed Array (ALFALFA) HI Survey. All the $\rm H\alpha$ images are obtained from the 2.16 m telescope, operated by Xinglong Observatory of the National Astronomical Observatories, Chinese Academy of Sciences. We provide the $\rm H\alpha$ fluxes and derive the global star formation rates (SFRs) of LSBGs after the Galactic extinction, internal extinction, and [NII] contamination correction. Comparing to normal star-forming galaxies, LSBGs have a similar distribution in the HI surface density ($\rm \Sigma_{HI}$), but their SFRs and star formation surface density ($\rm \Sigma_{SFR}$) are much lower. Our results show that the gas-rich LSBGs selected from the ALFALFA survey obviously deviate from the Kennicutt-Schmidt law, in the relation between the star formation surface density ($\rm \Sigma_{SFR}$) and the gas surface density ($\rm \Sigma_{gas}$). However, they follow the extended Schmidt law well when taking the stellar mass of the galaxy into consideration.