Interaction between the north-eastern boundary of Sgr A East and giant molecular clouds |
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| Authors: | Sungho Lee Soojong Pak Christopher J Davis Robeson M Herrnstein T R Geballe Paul T P Ho J Craig Wheeler |
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| Institution: | Astronomy Programme in SEES, Seoul National University, Shillim-Dong, Kwanak-Gu, Seoul 151-742, South Korea;Korea Astronomy Observatory, Whaam-Dong, Youseong-Gu, Taejeon 305-348, South Korea;Joint Astronomy Centre, University Park, 660 North A'ohöküPlace, Hilo, HI 96720, USA;Harvard–Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA;Gemini Observatory, 670 N. A'ohöküPlace, Hilo, HI 96720, USA;Astronomy Department, University of Texas, Austin, TX 78712, USA |
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| Abstract: | We have detected the v = 1 → 0 S(1) (λ= 2.1218 μm) and v = 2 → 1 S(1) (λ= 2.2477 μm) lines of H2 in the Galactic Centre, in a 90 × 27 arcsec2 region between the north-eastern boundary of the non-thermal source Sgr A East, and the giant molecular cloud (GMC) M?0.02 ? 0.07 . The detected H2 v = 1 → 0 S(1) emission has an intensity of 1.6–21 × 10?18 W m?2 arcsec?2 and is present over most of the region. Along with the high intensity, the large linewidths (FWHM = 40–70 km s?1) and the H2 v = 2 → 1 S(1) to v = 1 → 0 S(1) line ratios (0.3–0.5) can be best explained by a combination of C-type shocks and fluorescence. The detection of shocked H2 is clear evidence that Sgr A East is driving material into the surrounding adjacent cool molecular gas. The H2 emission lines have two velocity components at ～+50 and ～0 km s?1 , which are also present in the NH3(3, 3) emission mapped by McGary, Coil & Ho. This two-velocity structure can be explained if Sgr A East is driving C-type shocks into both the GMC M?0.02 ? 0.07 and the northern ridge of McGary et al. |
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| Keywords: | ISM: individual: Sgr A East ISM: individual: M?0 02 ? 0 07 ISM: lines and bands ISM: molecules Galaxy: centre infrared: ISM |
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