G23.33-0.30 is a 600 M _ { \odot } infrared dark molecular filament that exhibits large NH _ { 3 } velocity dispersions ( \sigma \sim 8 { km s ^ { -1 } } ) and bright , narrow NH _ { 3 } ( 3,3 ) line emission .
We have probed G23.33-0.30 at the < 0.1 pc scale and confirmed that the narrow NH _ { 3 } ( 3,3 ) line is emitted by four rare NH _ { 3 } ( 3,3 ) masers , which are excited by a large-scale shock impacting the filament .
G23.33-0.30 also displays a velocity gradient along its length , a velocity discontinuity across its width , shock-tracing SiO ( 5-4 ) emission extended throughout the filament , broad turbulent line widths in NH _ { 3 } ( 1,1 ) through ( 6,6 ) , CS ( 5-4 ) , and SiO ( 5-4 ) , as well as an increased NH _ { 3 } rotational temperature ( T _ { rot } ) and velocity dispersion ( \sigma ) associated with the shocked , blueshifted component .
The correlations among T _ { rot } , \sigma , and V _ { LSR } implies that the shock is accelerating , heating , and adding turbulent energy to the filament gas .
Given G23.33-0.30 ’ s location within the giant molecular cloud G23.0-0.4 , we speculate that the shock and NH _ { 3 } ( 3,3 ) masers originated from the supernova remnant W41 , which exhibits additional evidence of an interaction with G23.0-0.4 .
We have also detected the 1.3 mm dust continuum emission from at least three embedded molecular cores associated with G23.33-0.30 .
Although the cores have moderate gas masses ( M = 7 - 10 M _ { \odot } ) , their large virial parameters ( \alpha = 4 - 9 ) suggest that they will not collapse to form stars .
The turbulent line widths of the cores may indicate negative feedback due to the SNR shock .