Shock interactions between Sgr A East and its environments

[[abstract]]We have surveyed the interaction regions between Sgr A East and the surrounding molecular clouds in the H2 1-0 S(l) (2.1218 μm) line emission. The resulting data cube shows the distribution of the H2 emission both in space (with a resolution of about 2 arcsec) and in velocity (with a resolution of about 18 km s−1). Our data are compared with NH3(3,3) data from radio observations to investigate the gas kinematics. Based on the H2 1-0 S(l) line's intensity, its ratio to H2 2 - 1 S(1), and its gas kinematics, we conclude that the emitting H2 is excited by strong molecular shocks. We estimate shock velocities ( 100 km s−1) by comparing the H2 line profles with those of NH3, and derive an initial explosion energy of 0.2 − 4 × 1053 ergs. Such a high energy excludes a single normal supernova for the origin of Sgr A East. We examine other hypotheses, including the tidal disruption of a star by the supermassive black hole (Sgr A*), multiple supernovae, and a hypernova. We suggest that a hypernova, which is believed to originate from a collapsar or microquasar, is the most probable origin.[[fileno]]2010504010091[[department]]天文