Mapping the Extended HI Distribution of Three Dwarf Galaxies

TL;DR

This study uses the Green Bank Telescope to map the HI distribution of three dwarf galaxies, finding no extended HI skirts and confirming typical HI-to-optical size ratios, with no evidence of truncation.

Contribution

First large-scale HI maps of these dwarf galaxies using GBT, challenging previous reports of extended HI features from Effelsberg observations.

Findings

No extended HI skirts detected.

HI-to-optical size ratio is 2-3, typical for such galaxies.

No evidence of HI truncation at >/=10^19 atoms cm^-2.

Abstract

We present large field HI-line emission maps obtained with the single-dish Green Bank Telescope centered on the dwarf irregular galaxies Sextans A, NGC 2366, and WLM. We do not detect the extended skirts of emission associated with the galaxies that were reported from Effelsberg observations (Huchtmeier et al. 1981). The ratio of HI at 10^19 atoms cm^-2 to optical extents of these galaxies are instead 2--3, which is normal for this type of galaxy. There is no evidence for a truncation in the HI distribution >/=10^19 atoms cm^-2.