H3(+) spectroscopy and the ionization rate of molecular hydrogen in the central few parsecs of the galaxy

J Phys Chem A. 2013 Oct 3;117(39):9919-30. doi: 10.1021/jp400017s. Epub 2013 May 28.

Abstract

We report observations and analysis of infrared spectra of H3(+) and CO lines in the Galactic center, within a few parsecs of the central black hole, Sgr A*. We find a cosmic ray ionization rate typically an order of magnitude higher than outside the Galactic center. Notwithstanding, the elevated cosmic ray ionization rate is 4 orders of magnitude too short to match the proton energy spectrum, as inferred from the recent discovery of the TeV γ-ray source in the vicinity of Sgr A*.