We present a deep spectroscopic search for CO emission in the dwarf irregular galaxy DDO154, which has an Oxygen abundance of only 1/20 the solar value. The observations were conducted in order to constrain the CO-to-H2 conversion factor at low metallicity. No CO was detected, however, despite being one of the sensitive observations done towards galaxies of this type. We succeed in putting a strong lower limit on the conversion factor, at least 10 times the Galactic value. Our result supports previous studies which argue for a high conversion factor at low metallicity.
@article{arxiv.1011.3385,
title = {Deep CO Observations and the CO-to-H_2 Conversion Factor in DDO 154, a Low Metallicity Dwarf Irregular Galaxy},
author = {Shinya Komugi and Chikako Yasui and Naoto Kobayashi and Bunyo Hatsukade and Kotaro Kohno and Yoshiaki Sofue and Shiori Kyu},
journal= {arXiv preprint arXiv:1011.3385},
year = {2015}
}
Comments
11 pages, 4 figures. Accepted for publication in PASJ