Parker-Jeans Instability of Gaseous Disks Including the Effect of Cosmic Rays

Abstract

We use linear analysis to examine the effect of cosmic rays (CRs) on the Parker-Jeans instability of magnetized self-gravitating gaseous disks. We adopt a slab equilibrium model in which the gravity (including self-gravity) is perpendicular to the mid-plane, the magnetic field lies along the slab. CR is described as a fluid and only along magnetic field lines diffusion is considered. The linearised equations are solved numerically. The system is susceptible to Parker-Jeans instability. In general the system is less unstable when the CR diffusion coefficient is smaller (i.e., the coupling between the CRs and plasma is stronger). The system is also less unstable if CR pressure is larger. This is a reminiscence of the fact that Jeans instability and Parker instability are less unstable when the gas pressure is larger (or temperature is higher). Moreover, for large CR diffusion coefficient (or small CR pressure), perturbations parallel to the magnetic field are more unstable than those perpendicular to it. The other governing factor on the growth rate of the perturbations in different directions is the thickness of the disk or the strength of the external pressure on the disk. In fact, this is the determining factor in some parameter regimes.

arXiv comment19pages, 14figures submitted to ApJ

References in corpus (8)

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Cited by in corpus (11)

• The Parker Instability in Disk Galaxies
• Simulations of cosmic ray propagation
• The Role of the Parker Instability in Structuring the Interstellar Medium
• The Parker Instability with Cosmic Ray Streaming
• Interactions between Ultra-High-Energy Particles and Protogalactic Environments
• Dynamics of the Parker-Jeans instability of gaseous disks including the effect of cosmic rays
• Analysis of the magneto-rotational instability with the effect of cosmic-ray diffusion
• Outflows in the presence of cosmic rays and waves with cooling
• Outflows in the presence of cosmic rays and waves
• The influence of cosmic-rays on the magnetorotational instability
• Streaming cold cosmic ray back-reaction and thermal instabilities across the background magnetic field