Deuterium Fractionation across the Infrared Dark Cloud G034.77-00.55 interacting with the Supernova Remnant W44

Abstract

Supernova remnants (SNRs) may regulate star formation in galaxies. For example, SNR-driven shocks may form new molecular gas or compress pre-existing clouds and trigger the formation of new stars. To test this scenario, we measure the deuteration of $N_2{H}^{+}$, $D_{frac}^{N_2{H}^{+}}$, a well-studied tracer of pre-stellar cores, across the Infrared Dark Cloud (IRDC) G034.77-00.55, known to be experiencing a shock interaction with the SNR W44. We use N${}_2$H${}^{+}$ and N${}_2$D${}^{+}$ J=1-0 single pointing observations obtained with the 30m antenna at the Instituto de Radioastronomia Millimetrica to infer $D_{frac}^{N_2{H}^{+}}$ toward five positions across the cloud, namely a massive core, different regions across the shock front, a dense clump and ambient gas. We find $D_{frac}^{N_2{H}^{+}}$ in the range 0.03-0.1, several orders of magnitude larger than the cosmic D/H ratio ($\sim$10${}^{-5}$). Across the shock front, $D_{frac}^{N_2{H}^{+}}$ is enhanced by more than a factor of 2 ($D_{frac}^{N_2{H}^{+}}\sim$0.05-0.07) with respect to the ambient gas ($\le$0.03) and similar to that measured generally in pre-stellar cores. Indeed, in the massive core and dense clump regions of this IRDC we measure $D_{frac}^{N_2{H}^{+}}$}$\sim$0.1. We find enhanced deuteration of $N_2{H}^{+}$ across the region of the shock, at a level that is enhanced with respect to regions of unperturbed gas. It is possible that this has been induced by shock compression, which would then be indirect evidence that the shock is triggering conditions for future star formation. However, since unperturbed dense regions also show elevated levels of deuteration, further, higher-resolution studies are needed to better understand the structure and kinematics of the deuterated material in the shock region, e.g., if it still in relatively diffuse form or already organised in a population of low-mass pre-stellar cores.

Accepted for publication on A&A; 8 pages, 5 figures

References in corpus (17)

• Slow Star Formation in Dense Gas: Evidence and Implications
• Star Formation in Disk Galaxies. I. Formation and Evolution of Giant Molecular Clouds via Gravitational Instability and Cloud Collisions
• Survey of ortho-H2D+(1_{1,0}-1_{1,1}) in dense cloud cores
• The N2D+/N2H+ ratio as an evolutionary tracer of Class 0 protostars
• Observational Evidence of Dynamic Star Formation Rate in Milky Way Giant Molecular Clouds
• Searching for massive pre--stellar cores through observations of N2H+ and N2D+
• Chemical evolution in the early phases of massive star formation II: Deuteration
• Massive and low-mass protostars in massive "starless" cores
• Distributed Low-Mass Star Formation in the IRDC G34.43+00.24
• The ALMA Survey of 70 $\mu$m Dark High-mass Clumps in Early Stages (ASHES). IV. Star formation signatures in G023.477
• ALMA-IRDC: Dense gas mass distribution from cloud to core scales
• Negative and Positive Feedback from a Supernova Remnant with SHREC: A detailed Study of the Shocked Gas in IC443
• A timeline for massive star-forming regions via combined observation of o-H${}_2$D${}^{+}$ and N${}_2$D${}^{+}$
• The L1157-B1 astrochemical laboratory: testing the origin of DCN
• Infrared Dark Clouds and high-mass star formation activity in Galactic Molecular Clouds
• Star Formation in a Strongly Magnetized Cloud
• An X-ray View of Two Infrared Dark Clouds G034.43+00.24 and G035.39-00.33

Cited by in corpus (3)

• Interaction between the Supernova Remnant W44 and the Infrared Dark Cloud G034.77-00.55: shock induced star formation?
• Chemical complexity in star formation induced by stellar feedback: cores shock-formed by the supernova remnant W44
• Chemistry of Dark Molecular Clouds