The Role of the Parker Instability in Structuring the Interstellar Medium

Abstract

The Parker instability, a Rayleigh-Taylor like instability of thermal gas supported against gravity by magnetic fields and cosmic rays, is thought to be dynamically important for galaxy evolution, possibly promoting molecular cloud formation and the galactic dynamo. In previous work, we examined the effect of three different cosmic ray transport models on the Parker instability: decoupled (${\gamma }_c=0$), locked to the thermal gas (${\gamma }_c=4/3$) and coupled to the gas with streaming by self-confinement. We expand upon that work here by considering radiative cooling, a smooth gravitational potential, and simulations into the nonlinear regime. We determine that cosmic ray transport away from compression points, whether by diffusion or streaming, is the largest driver of the instability. Heating due to cosmic ray streaming is also destabilizing and especially affects the nonlinear regime. While cooling de-pressurizes the dense gas, streaming cosmic rays heat and inflate the diffuse extraplanar gas, greatly modifying the phase structure of the medium. In 3D, we find that the fastest growth favors short wavelength modes in the horizontal direction perpendicular to the background magnetic field; this is imprinted on Faraday rotation measure maps that may be used to detect the Parker instability. The modifications to the Parker instability that we observe in this work have large implications for the structure and evolution of galaxies, and they highlight the major role that cosmic rays play in shaping their environments.

arXiv comment26 pages, 22 figures, 1 table, accepted to ApJ

References in corpus (31)

• A Multi-Code Analysis Toolkit for Astrophysical Simulation Data
• The effect of photo-ionization on the cooling rates of enriched, astrophysical plasmas
• LCDM-based models for the Milky Way and M31 I: Dynamical Models
• A direct dynamical measurement of the Milky Way's disk surface density profile, disk scale length, and dark matter profile at 4 kpc < R < 9 kpc
• The Milky Way's Kiloparsec Scale Wind: A Hybrid Cosmic-Ray and Thermally Driven Outflow
• Stars, Gas, and Dark Matter in the Solar Neighborhood
• Cosmic-ray Driven Outflows in Global Galaxy Disk Models
• Launching cosmic-ray-driven outflows from the magnetized interstellar medium
• Numerical Simulations of Multiphase Winds and Fountains from Star-Forming Galactic Disks: I. Solar Neighborhood TIGRESS Model
• Global simulations of galactic winds including cosmic ray streaming
• A Solution Accurate, Efficient and Stable Unsplit Staggered Mesh Scheme for Three Dimensional Magnetohydrodynamics
• Towards simulating star formation in the interstellar medium
• The Fermi Bubbles: Supersonic AGN Jets with Anisotropic Cosmic Ray Diffusion
• Evidence for an Additional Heat Source in the Warm Ionized Medium of Galaxies
• The Role of Cosmic Ray Transport in Shaping the Simulated Circumgalactic Medium
• Cosmic ray-driven galactic winds: streaming or diffusion?
• Role of Cosmic Rays in the Circumgalactic Medium
• The Fermi Bubbles. II. The Potential Roles of Viscosity and Cosmic Ray Diffusion in Jet Models
• Cosmic ray driven dynamo in galactic disks. A parameter study
• The Effect of Cosmic Ray Diffusion on the Parker Instability
• Cosmic Ray Heating of the Warm Ionized Medium
• Structure and Stability of Phase Transition Layers in the Interstellar Medium
• Dynamo activities driven by magneto-rotational instability and Parker instability in galactic gaseous disk
• Nonlinear Parker Instability with the Effect of Cosmic-Ray Diffusion
• The Parker Instability in Disk Galaxies
• Parker-Jeans Instability of Gaseous Disks Including the Effect of Cosmic Rays
• Formation of Interstellar Clouds: Parker Instability with Phase Transitions
• The Parker Instability with Cosmic Ray Streaming
• Testing a Dynamical Equilibrium Model of the Extraplanar Diffuse Ionized Gas in NGC 891
• The Parker Instability in a Thick Galactic Gaseous Disk: I. Linear Stability Analysis and Nonlinear Final Equilibria
• A Comparative Study of the Parker Instability under Three Models of the Galactic Gravity

Cited by in corpus (22)

• The Impact of Cosmic Rays on Thermal Instability in the Circumgalactic Medium
• Cosmic Ray Transport, Energy Loss, and Influence in the Multiphase Interstellar Medium
• Simulations of cosmic ray propagation
• Cosmic-Ray Transport in Varying Galactic Environments
• The Galactic dynamics revealed by the filamentary structure in atomic hydrogen emission
• Cosmic Ray Driven Outflows from the Large Magellanic Cloud: Contributions to the LMC Filament
• Cosmic rays across the star-forming galaxy sequence. I: Cosmic ray pressures and calorimetry
• The Launching of Cosmic Ray Driven Outflows
• The Cosmic Ray Staircase: the Outcome of the Cosmic Ray Acoustic Instability
• The structure and characteristic scales of the HI gas in galactic disks
• Turbulent Reacceleration of Streaming Cosmic Rays
• Steady states of the Parker instability
• On the spatial and temporal non-locality of dynamo mean-field effects in supersonic interstellar turbulence
• Magnetohydrodynamic instabilities in a self-gravitating rotating cosmic plasma
• Outflows in the presence of cosmic rays and waves
• Outflows in the presence of cosmic rays and waves with cooling
• The magnetic field of the Radcliffe Wave: starlight polarization at nearest approach to the Sun
• The Impact of Cosmic Ray Injection on Magnetic Flux Tubes in a Galactic Disk
• Hot magnetic halo of NGC628 (M74)
• CHANG-ES XXXVII. Effects of spectral aging on radio scale heights
• Magnetic fields and hot gas in M101
• Place of the Radcliffe Wave in the Local System