The Interaction between the Supernova Remnant W41 and the Filamentary Infrared Dark Cloud G23.33-0.30

Abstract

G23.33-0.30 is a 600  M ⊙ infrared dark molecular filament that exhibits large NH 3 velocity dispersions ( σ  ∼ 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, and 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 ( σ ) associated with the shocked, blueshifted component. The correlations among T rot , σ , and V LSR imply 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 (SNR) 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 ⊙ ), their large virial parameters ( α  = 4–9) suggest that they will not collapse to form stars. The turbulent line widths of the ( α  > 1) cores may indicate negative feedback due to the SNR shock.