We report a discovery of shocked gas from the supernova remnant ( SNR ) G357.7+0.3 .
Our millimeter and submillimeter observations reveal broad molecular lines of CO ( 2-1 ) , CO ( 3-2 ) , CO ( 4-3 ) , ^ { 13 } CO ( 2-1 ) and ^ { 13 } CO ( 3-2 ) , HCO ^ { + } and HCN using HHSMT , Arizona 12-Meter Telescope , APEX and MOPRA Telescope .
The widths of the broad lines are 15-30 kms ^ { -1 } , and the detection of such broad lines is unambiguous , dynamic evidence showing that the SNR G357.7+0.3 is interacting with molecular clouds .
The broad lines appear in extended regions ( > 4.5 ^ { \prime } \times 5 ^ { \prime } ) .
We also present detection of shocked H _ { 2 } emission in mid-infrared but lacking ionic lines using the Spitzer IRS observations to map a few arcmin area .
The H _ { 2 } excitation diagram shows a best-fit with a two-temperature LTE model with the temperatures of \sim 200 and 660 K. We observed [ C II ] at 158 \mu m and high-J CO ( 11-10 ) with the GREAT on SOFIA .
The GREAT spectrum of [ C II ] , a 3 \sigma detection , shows a broad line profile with a width of 15.7 km ^ { -1 } that is similar to those of broad CO molecular lines .
The line width of [ C II ] implies that ionic lines can come from a low-velocity C-shock .
Comparison of H _ { 2 } emission with shock models shows that a combination of two C-shock models is favored over a combination of C- and J-shocks or a single shock .
We estimate the CO density , column density , and temperature using a RADEX model .
The best-fit model with n ( H _ { 2 } ) = 1.7 \times 10 ^ { 4 } cm ^ { -3 } , N ( CO ) = 5.6 \times 10 ^ { 16 } cm ^ { -2 } , and T = 75 K can reproduce the observed millimeter CO brightnesses .