CH 3 GHz Observations of the Galactic Center

Abstract

A 3 $\times$ 3 map of the Galactic Center was made at 9$\arcmin$ resolution and 10$\arcmin$ spacing in the CH ${}^2{\Pi }_{1/2}$, J=1/2, F=1-1 transition at 3335 MHz. The CH emission shows a velocity extent that is nearly that of the CO(1-0) line, but the CH line profiles differ markedly from the CO. The 3335 MHz CH transition primarily traces low-density molecular gas and our observations indicate that the mass of this component within $\sim$ 30 pc of the Galactic Center is $\sim$ 9 $\times$ 10${}^6$ M${}_{\odot }$. The CO-H${}_2$ conversion factor obtained for the low-density gas in the mapped region is greater than that thought to apply to the dense molecular gas at the Galactic Center. In addition to tracing the low-density molecular gas at the Galactic Center, the CH spectra show evidence of emission from molecular clouds along the line of sight both in the foreground and background. The scale height of these clouds ranges from 27 - 109 pc, consistent with previous work based on observations of molecular clouds in the inner Galaxy.

arXiv comment29 pages, 12 figures

References in corpus (6)

• The Milky Way in Molecular Clouds: A New Complete CO Survey
• A FUSE Survey of Interstellar Molecular Hydrogen in Translucent Clouds
• The AST/RO Survey of the Galactic Center Region. I. The Inner 3 Degrees
• Comparative Chemistry of Diffuse Clouds IV: CH
• The Scaleheight of Giant Molecular Clouds is Less than that of Smaller Clouds
• CH 3 GHz Observations of Molecular Clouds Along the Galactic Plane

Cited by in corpus (6)

• Spatial distribution of interstellar gas in the innermost 3 kpc of our Galaxy
• Chemical Abundances of Luminous Cool Stars in the Galactic Center from High-Resolution Infrared Spectroscopy
• Interacting Cosmic Rays with Molecular Clouds: A Bremsstrahlung Origin of Diffuse High Energy Emission from the Inner 2deg by 1deg of the Galactic Center
• 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
• Carbon Fractionation in PDRs
• The Dense Gas Fraction in Galactic Center Clouds