Interaction between the north-eastern boundary of Sgr a East and giant molecular clouds

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 H₂v = 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.