We report a new 1-pc ( 30 \arcsec ) resolution CS ( J = 2 - 1 ) line map of the central 30 pc of the Galactic Center ( GC ) , made with the Nobeyama 45m telescope .
We revisit our previous study of the extraplanar feature called polar arc ( PA ) , which is a molecular cloud located above SgrA* with a velocity gradient perpendicular to the Galactic plane .
We find that the PA can be traced back to the Galactic disk .
This provides clues of the launching point of the PA , roughly 6 \times 10 ^ { 6 } years ago .
Implications of the dynamical time scale of the PA might be related to the Galactic Center Lobe ( GCL ) at parsec scale .
Our results suggest that in the central 30 pc of the GC , the feedback from past explosions could alter the orbital path of the molecular gas down to the central tenth of parsec .
In the follow-up work of our new CS ( J = 2 - 1 ) map , we also find that near the systemic velocity , the molecular gas shows an extraplanar hourglass-shaped feature ( HG-feature ) with a size of \sim 13 pc .
The latitude-velocity diagrams show that the eastern edge of the HG-feature is associated with an expanding bubble B1 , \sim 7 pc away from SgrA* .
The dynamical time scale of this bubble is \sim 3 \times 10 ^ { 5 } years .
This bubble is interacting with the 50 km s ^ { -1 } cloud .
Part of the molecular gas from the 50 km s ^ { -1 } cloud was swept away by the bubble to b = -0.2 \arcdeg .
The western edge of the HG-feature seems to be the molecular gas entrained from the 20 km s ^ { -1 } cloud towards the north of the Galactic disk .
Our results suggest a fossil explosion in the central 30 pc of the GC a few 10 ^ { 5 } years ago .