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

TL;DR

This study investigates how the supernova remnant W41 interacts with the infrared dark cloud G23.33-0.30, revealing shock-induced masers, turbulence, and heating effects that influence the cloud's physical state.

Contribution

It provides new evidence linking W41's shock impact to the excitation of NH$_3$(3,3) masers and turbulence in G23.33-0.30, highlighting the role of supernova remnants in molecular cloud dynamics.

Findings

Detection of NH$_3$(3,3) masers excited by shocks.

Identification of shock-tracing SiO emission across the filament.

Observation of increased temperature and turbulence linked to the supernova remnant.

Abstract

G23.33-0.30 is a 600 $M_{\odot}$ infrared dark molecular filament that exhibits large NH$_3$ velocity dispersions ($\sigma \sim 8 \ \rm{km \ s^{-1}}$) 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 ($T_{\rm{rot}}$) and velocity dispersion ($\sigma$) associated with the shocked, blueshifted component. The correlations among $T_{\rm{rot}}$, $\sigma$, and $V_{\rm{LSR}}$ 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.