In section 6. Interstellar and circumstellar matter
ALMA hints at the existence of an unseen reservoir of diffuse molecular gas in the Galactic bulge
While studying chemistry in local diffuse molecular gas with the ALMA array, the authors of this work serendipitously found mm-wave molecular absorption at -200 km/s < v −140 km/s towards the Galactic bulge. Combining their results with the near-infrared dust extinction in Shultheis et al. (2014), the authors argue that their finding suggests the existence of an unseen reservoir of diffuse molecular gas in the galactic bulge. The physical properties and total mass of these molecular gas in the bulge suggested by this work will need to be determined with future observations and re-analysis of existing archival near-infrared dust extinction and HI data.