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Molecular Hydrogen Emission from the Inner 400 Parsecs of the Galaxy

Soojong Pak, D. T. Jaffe, L. D. Keller

astro-pharXiv:astro-ph/9604174

Abstract

We have mapped the H2 v=1-0 S(1) (λ=2.1215 ) emission line along a 400 pc long strip and in a 50 pc region in the Galactic center. There is H2 emission throughout the surveyed region. The typical de-reddened (AK = 2.5 mag) surface brightness, about 3 X 10-5 ergs/s/cm2/sr, is similar to the surface brightness in large-scale photon-dominated regions in the galactic disk. We investigate two possible excitation mechanisms for the H2 emission: UV-excitation by photons from OB stars, and shock waves, and conclude that UV-excitation is more likely. The total H2 v=1-0 S(1) luminosity in the inner 400 pc region of the Galaxy is 8000 Lsun. The ratio of the H2 to far-IR luminosity in the inner 400 pc of the Galaxy agrees with that in starburst galaxies and ultraluminous infrared bright galaxies.

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