An expanding shell-like molecular cloud near the Galactic center arc

We found, from the data of our CS (J = 1-0/2-1) survey with the Nobeyama 45 m telescope, that a molecular cloud associated with the ''vertical filaments'' of the Galactic center are has a shell-like structure and is expanding with a velocity of 20 km s(-1). The limb of the shell has high density, n(H-2)= 6 x 10(4) cm(-3). The shell may have originated from 10-100 supernovae within the last 10(5) yr. At the point of contact with the filaments, the limb of the shell is deformed and the filaments are bent in the opposite direction. These compensative deformations suggest that the shell is dynamically interacting with the filaments. The interaction may activate relativistic electrons in the Galactic center are.