Odin observations of H2O in the Galactic Centre

Abstract

The Odin satellite has been used to detect emission and absorption in the 557-GHz H2O line in the Galactic Centre towards the Sgr A* Circumnuclear Disk (CND), and the Sgr A +20 km/s and +50 km/s molecular clouds. Strong broad H2O emission lines have been detected in all three objects. Narrow H2O absorption lines are present at all three positions and originate along the lines of sight in the 3-kpc Spiral Arm, the -30 km/s Spiral Arm and the Local Sgr Spiral Arm. Broad H2O absorption lines near -130 km/s are also observed, originating in the Expanding Molecular Ring. A new molecular feature (the ``High Positive Velocity Gas'' - HPVG) has been identified in the positive velocity range of ~ +120 to +220 km/s, seen definitely in absorption against the stronger dust continuum emission from the +20 km/s and +50 km/s clouds and possibly in emission towards the position of Sgr A* CND. The 548-GHz H2_18O isotope line towards the CND is not detected at the 0.02 K (rms) level.

5 pages, 3 figures, accepted by A&A, special Odin Letters issue

References in corpus (6)

• Closest Star Seen Orbiting the Supermassive Black Hole at the Centre of the Milky Way
• Water Abundance in Molecular Cloud Cores
• AST/RO Observations of Atomic Carbon near the Galactic Center
• SWAS and Arecibo observations of H2O and OH in a diffuse cloud along the line-of-sight to W51
• Cold H2O and CO ice and gas toward the Galactic Center
• Molecular Hydrogen Emission from the Inner 400 Parsecs of the Galaxy

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• Ground-state ammonia and water in absorption towards Sgr B2
• Odin observations of the Galactic centre in the 118-GHz band. Upper limit to the O2 abundance
• Gas and dust in the star-forming region rho Oph A: II. The gas in the PDR and in the dense cores
• High-speed molecular cloudlets around the Galactic Center supermassive black hole
• Herschel HIFI Observations of the Sgr A +50 km/s Cloud. Deep Searches for O2 in Emission and Foreground Absorption
• Upper limits to the water abundance in starburst galaxies
• Odin observations of ammonia in the Sgr A +50 km/s Cloud and Circumnuclear Disk
• Herschel water maps towards the vicinity of the black hole Sgr A*