New temperature maps of the Central Molecular Zone

Top of the Arxiv this morning is a great paper I was happy to collaborate on with Adam Ginsburg (ESO) and a large team of scientists from around the world, showing new temperature maps of the Central Molecular Zone. The Central Molecular Zone, or CMZ, occupies some 500 pc around the centre of our Galaxy (around 1600 light years), which hosts around 10% of all the molecular gas in the Galaxy. We know that the gas clouds in the region are hotter than similar clouds further out in the Galaxy, and because of the strong gravity so close to the Galactic Centre they show high velocities and strong turbulence. The conditions are not too dissimilar from what we observe at the centres of other galaxies, in particular galaxies in the early Universe; as such the CMZ is a useful local template for these distant galaxies.

These new maps are the result of 150 hours of observations with the sub-millimeter APEX telescope in the Atacama desert in Chile, and they are the largest consistent temperature maps of the CMZ to date. The temperature was derived from spectral line observations of formaldehyde (H2CO) using a combination of measurements and modelling. The whole data processing and analysis procedure was a major effort and much kudos to Adam for doing a phenomenal job. Overall the maps are broadly consistent with previous measurements using different molecules, but no previous studies have covered such a large area of the CMZ with one campaign so many aspects of the measurements are completely new.

The data will be a fantastic reference set for scientists studying other aspects of the CMZ, such as star formation and cloud dynamics, as well as those studying the conditions at the hearts of other galaxies. Together with today's paper, the data, maps and all the source code used in the project have been made publicly available.