The thermal state of molecular clouds in the Galactic center: Evidence for non-photon-driven heating

Abstract

We have used the Atacama Pathfinder Experiment (APEX) 12 m telescope at 218 GHz to observe molecular clouds simultaneously in the JKaKc = 3 03 → 202, 322 → 221, and 321 → 220 transitions of para-H2CO to determine kinetic temperatures of the dense gas in the central molecular zone of the Galaxy. Gas kinetic temperatures for individual molecular clouds range from 55 to 125 K or even higher. The molecular clouds at high temperatures may be heated by turbulent dissipation and/or cosmic-rays. Copyright © International Astronomical Union 2014.