SIMBAD references

Carbon monoxide (CO) is one of the primary coolants of gas and an easily accessible tracer of molecular gas in spiral galaxies, but it is unclear if CO plays a similar role in metal-poor dwarfs. We carried out a deep observation with IRAM 30 m to search for CO emission by targeting the brightest far-IR peak in a nearby extremely metal-poor galaxy, Sextans A, with 7% solar metallicity. A marginal signal of CO J = 1 - 0 emission is seen, which is already faint enough to place a strong constraint on the conversion factor (αCO) from the CO luminosity to the molecular gas mass that is derived from the spatially resolved dust-mass map. The αCO is at least seven hundred times the Milky Way value. This indicates that CO emission is exceedingly weak in Sextans A, challenging its role as a coolant in extremely metal-poor galaxies.