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Interaction between the Northeastern Boundary of Sgr A East and Giant Molecular Clouds

Sungho Lee·Soojong Pak·Christopher J. Davis·Robeson M. Herrnstein·T. R. Geballe·Paul T. P. Ho·J. Craig Wheeler
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Abstract

We have detected the v=1-0 S(1) (2.1218 um) and v=2-1 S(1) (2.2477 um) lines of H_2 in the Galactic centre, in a 90 x 27 arcsec region between the northeastern boundary of the non-thermal source, Sgr A East, and the giant molecular cloud (GMC) M-0.02-0.07. The detected H_2 v=1-0 S(1) emission has an intensity of 1.6 - 21 x 10^-18 W/m^2/arcsec^2 and is present over most of the region. Along with the high intensity, the broad line widths (FWHM = 40 - 70 km/s) and the 2-1 S(1) / 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 H_2 is clear evidence that Sgr A East is driving material into the surrounding adjacent cool molecular gas. The H_2 emission lines have two velocity components at about +50 km/s and 0 km/s, which are also present in the NH_3(3,3) emission mapped by McGary, Coil, and Ho (2001, ApJ, 559, 326). 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, Coil, and Ho (2001).

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Sungho Lee, Soojong Pak, Christopher J. Davis, Robeson M. Herrnstein, T. R. Geballe, Paul T. P. Ho, J. Craig Wheeler. 2003-02-16. Interaction between the Northeastern Boundary of Sgr A East and Giant Molecular Clouds. https://doi.org/10.1046/j.1365-8711.2003.06425.x

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