Narayanan, Desika, Krumholz, Mark R., Ostriker, Eve C., and Hernquist, Lars. 2012. "A general model for the CO-H2 conversion factor in galaxies with applications to the star formation law." Monthly Notices of the Royal Astronomical Society 421:3127-3146. https://doi.org/10.1111/j.1365-2966.2012.20536.x
The most common means of converting an observed CO line intensity into a molecular gas mass requires the use of a conversion factor (XCO). While in the Milky Way this quantity does not appear