H3+ Spectroscopy and the Ionization Rate of Molecular Hydrogen in the Central Few Parsecs of the Galaxy

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 gamma-ray source in the vicinity of Sgr A*.

18 pages, 12 figures, Accepted for publication at the Journal of Physical Chemistry A "Oka Festschrift: Celebrating 45 Years of Astrochemistry"

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Cited by in corpus (22)

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• Physical conditions in the central molecular zone inferred by H3+
• Cloud-cloud collision as drivers of the chemical complexity in Galactic Centre molecular clouds
• The Central 300 pc of the Galaxy probed by infrared spectra of H${}_3^{+}$ and CO: part I. Predominance of warm and diffuse gas and high H${}_2$ ionization rate
• The Excitation of HCN and HCO+ in the Galactic Center Circumnuclear Disk
• Propargylimine in the laboratory and in space: millimetre-wave spectroscopy and first detection in the ISM
• CMZoom: Survey Overview and First Data Release
• Chemical Features in the Circumnuclear Disk of the Galactic Center
• Abundant Methanol Masers but no New Evidence for Star Formation in GCM0.253+0.016
• Exceptional AGN-driven turbulence inhibits star formation in the 3C 326N radio-galaxy
• CMZoom II: Catalog of Compact Submillimeter Dust Continuum Sources in the Milky Way's Central Molecular Zone
• Widespread Rotationally-Hot Hydronium Ion in the Galactic Interstellar Medium
• Hot Molecular Gas in the Circumnuclear Disk
• Enhanced formation of interstellar complex organic molecules on carbon monoxide ice
• Processing of hydroxylamine, NH2OH, an important prebiotic precursor, on interstellar ices
• 2-aminooxazole in astrophysical environments: IR spectra and destruction cross sections for energetic processing
• Theoretical study of ionization profiles of molecular clouds near supernova remnants: Tracing the hadronic origin of GeV gamma radiation
• Revealing the Physical Conditions around Sgr A* using Bayesian Inference -- I. Observations and Radiative Transfer
• Chemical templates of the Central Molecular Zone. Shock and protostellar object signatures under Galactic Center conditions
• Origin of X-ray and gamma-ray emission from the Galactic central region