The Drag Instability in a 2D Isothermal C-shock

Abstract

We extend the linear analysis of the drag instability in a 1D perpendicular isothermal C-shock by Gu & Chen to 2D perpendicular and oblique C-shocks in the typical environment of star-forming clouds. Simplified dispersion relations are derived for the unstable modes. We find that the mode property of the drag instability generally depends on the ratio of the transverse (normal to the shock flow) to longitudinal (along the shock flow) wavenumber. For the transversely large-scale mode, the growth rate and wave frequency of the drag instability in a 2D shock resemble those in a 1D shock. For the transversely small-scale mode, the drag instability is characterized by an unstable mode coupled with an acoustic mode primarily along the transverse direction. When the shock is perpendicular or less oblique, there exists a slowly propagating mode, which can potentially grow into a nonlinear regime and contribute to the maximum growth of the instability. In contrast, when the shock is more oblique, this slowly propagating unstable mode disappears, and the maximum growth of the drag instability is likely contributed from the transversely large-scale mode (i.e., almost 1D mode). In all cases that we consider, the magnitude of the density perturbations is significantly larger than that of the velocity and magnetic field perturbations, implying that the density enhancement governs the dynamics in the linear regime of the instability. A few issues in the linear analysis, as well as the possible astrophysical implications, are also briefly discussed.

arXiv comment20 pages, 11 figures

References in corpus (35)

• Star Formation in the Milky Way and Nearby Galaxies
• Interstellar Turbulence I: Observations and Processes
• Dissipation in Compressible MHD Turbulence
• The Energy Dissipation Rate of Supersonic, Magnetohydrodynamic Turbulence in Molecular Clouds
• Kinetic Energy Decay Rates of Supersonic and Super-Alfvenic Turbulence in Star-Forming Clouds
• Protoplanetary Disk Turbulence Driven by the Streaming Instability: Non-Linear Saturation and Particle Concentration
• Star Formation Efficiencies and Lifetimes of Giant Molecular Clouds in the Milky Way
• Investigating the Cosmic-Ray Ionization Rate in the Galactic Diffuse Interstellar Medium through Observations of H3+
• Turbulent molecular clouds
• The Second Survey of the Molecular Clouds in the Large Magellanic Cloud by NANTEN. II. Star Formation
• Giant Molecular Clouds in M33 - I. BIMA All Disk Survey
• SiO line emission from C-type shock waves : interstellar jets and outflows
• Magnetically Regulated Star Formation in 3D: The Case of Taurus Molecular Cloud Complex
• A census of dense cores in the Aquila cloud complex: SPIRE/PACS observations from the Herschel Gould Belt survey
• Quiescent Cores and the Efficiency of Turbulence-Accelerated, Magnetically Regulated Star Formation
• Formation of Magnetized Prestellar Cores with Ambipolar Diffusion and Turbulence
• Two Mass Distributions in the L 1641 Molecular Clouds: The Herschel connection of Dense Cores and Filaments in Orion A
• Short GMC lifetimes: an observational estimate with the PdBI Arcsecond Whirlpool Survey (PAWS)
• Probing the Turbulence Dissipation Range and Magnetic Field Strengths in Molecular Clouds
• GMC Evolutions in the Nearby Spiral Galaxy M33
• A general theory for the lifetimes of giant molecular clouds under the influence of galactic dynamics
• Physical Processes in Star Formation
• Magnetically Regulated Star Formation in Turbulent Clouds
• Sub-Alfvenic Non-Ideal MHD Turbulence Simulations with Ambipolar Diffusion: II. Comparison with Observation, Clump Properties, and Scaling to Physical Units
• Origin of CH+ in diffuse molecular clouds warm H2 and ion-neutral drift
• Dust grains and the structure of steady C-type magnetohydrodynamic shock waves in molecular clouds
• Determination of Stochastic Acceleration Model Characteristics in Solar Flares
• The Wardle Instability in Interstellar Shocks: I. Nonlinear Dynamical Evolution
• Observational Determination of the Turbulent Ambipolar Diffusion Scale and Magnetic Field Strength in Molecular Clouds
• Ambipolar Diffusion in Action: Transient C shock Structure and Prestellar Core Formation
• CH as a Molecular Gas Tracer and C-Shock Tracer Across a Molecular Cloud Boundary in Taurus
• Signatures of fast and slow magnetohydrodynamic shocks in turbulent molecular clouds
• Probing the Turbulence Dissipation Range and Magnetic Field Strengths in Molecular Clouds. II. Directly Probing the Ion-neutral Decoupling Scale
• Probing the Turbulent Ambipolar Diffusion Scale in Molecular Clouds with Spectroscopy
• The Drag Instability in a 1D Isothermal C-Shock

Cited by in corpus (1)

• Revealing the drag instability in one-fluid nonideal MHD simulations of a 1D isothermal C-shock