Oral Presentation

Carbon monoxide in an extremely metal poor galaxy

Author(s): Yong Shi (Nanjing University)

Presenter: Yong Shi (Nanjing University)

All present-day star formation in Spiral galaxies takes place in clouds of molecular gas with carbon monoxide as the most accessible tracer. Because of no detection of carbon monoxide in galaxies with the metallicity below 10% of Solar value, however, it is unclear if molecular gas is the prerequisite for stars to form in the early Universe when metals are scarce; or instead stars may just form in atomic gas as suggested by some models. We here report a detection of carbon monoxide in a galaxy at 7% of Solar metallicity, along with two additional detections at somewhat higher metallicity. With archived infrared data, we show that carbon monoxide traces abundant molecular gas in these galaxies, suggesting the presence of rich molecular gas in the early Universe.