The Kinematics of Molecular Cloud Cores in the Presence of Driven and Decaying Turbulence: Comparisons with Observations

Abstract

In this study we investigate the formation and properties of prestellar and protostellar cores using hydrodynamic, self-gravitating Adaptive Mesh Refinement simulations, comparing the cases where turbulence is continually driven and where it is allowed to decay. We model observations of these cores in the C${}^{18}$O$(2\to 1)$, NH${}_3(1,1)$, and N${}_2$H${}^{+}(1\to 0)$ lines, and from the simulated observations we measure the linewidths of individual cores, the linewidths of the surrounding gas, and the motions of the cores relative to one another. Some of these distributions are significantly different in the driven and decaying runs, making them potential diagnostics for determining whether the turbulence in observed star-forming clouds is driven or decaying. Comparing our simulations with observed cores in the Perseus and $\rho$ Ophiuchus clouds shows reasonably good agreement between the observed and simulated core-to-core velocity dispersions for both the driven and decaying cases. However, we find that the linewidths through protostellar cores in both simulations are too large compared to the observations. The disagreement is noticably worse for the decaying simulation, in which cores show highly supersonic infall signatures in their centers that decrease toward their edges, a pattern not seen in the observed regions. This result gives some support to the use of driven turbulence for modeling regions of star formation, but reaching a firm conclusion on the relative merits of driven or decaying turbulence will require more complete data on a larger sample of clouds as well as simulations that include magnetic fields, outflows, and thermal feedback from the protostars.

18 pages, 12 figures, accepted to AJ

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Cited by in corpus (17)

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• The ALMA Survey of 70 μm Dark High-mass Clumps in Early Stages (ASHES). VIII. Dynamics of Embedded Dense Cores
• Synthetic Observations of Magnetic Fields in Protostellar Cores
• Molecular Emission Line Formation in Prestellar Cores
• The Life Cycle of the Central Molecular Zone. II: Distribution of atomic and molecular gas tracers
• Identifying Tools for Comparing Simulations and Observations of Spectral-line Data Cubes
• Fragmentation and Kinematics of dense molecular cores in the filamentary infrared-dark cloud G011.11-0.12
• An Exploration of the Statistical Signatures of Stellar Feedback
• The Interplay of Turbulence & Magnetic Fields in Star-Forming Regions: Simulations and Observations
• A turbulent origin for the complex envelope kinematics in the young low-mass core Per-Bolo 58
• The Astrochemical Evolution of Turbulent Giant Molecular Clouds : I - Physical Processes and Method of Solution for Hydrodynamic, Embedded Starless Clouds
• Understanding biases in measurements of molecular cloud kinematics using line emission
• The Kinematic and Chemical Properties of a Potential Core-Forming Clump: Perseus B1-E
• A Guide to Comparisons of Star Formation Simulations with Observations