Searches for Extremely Metal Poor Galaxies using ALFALFA-selected Dwarf Galaxies

TL;DR

This study used ALFALFA-selected dwarf galaxies to search for extremely metal-poor galaxies, but found none, providing insights into the metallicity distribution of nearby dwarf systems.

Contribution

It introduces a non-standard selection method using ALFALFA data to identify potential XMP galaxies among dwarf systems.

Findings

No extremely metal-poor galaxies were detected.

One galaxy had a low oxygen abundance of 6% solar.

A galaxy with high oxygen abundance suggests a tidal origin.

Abstract

We present a study of nearby dwarf galaxies selected from the ALFALFA blind HI survey. A primary goal of the project was to utilize a non-standard selection method with the hope of detecting previously unrecognized extremely metal-poor (XMP) galaxies. The study was motivated by the recent discovery of two XMP galaxies $-$ Leo P and Leoncino $-$ which were both originally found via the ALFALFA survey. We have obtained narrowband H$\alpha$ images for 42 dwarf systems, many of which are located in the local void in front of the Pisces-Perseus Supercluster. Spectra for eleven of the best candidates resulted in the determination of metal abundances for ten of the systems. None were found to be extremely metal poor, although one system (AGC 123350) was found to have an oxygen abundance of log(O/H)+12 = 7.46, or $\sim$6\% solar. One of the galaxies in our sample exhibits a high oxygen abundance for its luminosity, suggesting the possibility that it may have a tidal origin.