Influence of energy exchange of electrons and ions on the long-wavelength thermal instability in magnetized astrophysical objects

Abstract

We investigate thermal instability in an electron-ion magnetized plasma relevant to galaxy clusters, solar corona, and other two-component astrophysical objects. We apply the multicomponent plasma approach when the dynamics of all the species are considered separately through electric field perturbations. General expressions for perturbations obtained in this paper can be applied for a wide range of multicomponent astrophysical and laboratory plasmas also containing the neutrals, dust grains, and other species. We assume that background temperatures of electrons and ions are different and include the energy exchange in thermal equations. We take into account the dependence of collision frequency on density and temperature perturbations. The cooling-heating functions are taken as different ones for electrons and ions. As a specific case, we consider a condensation mode of thermal instability of long-wavelength perturbations when the dynamical time is smaller than a time during which the particles cover the wavelength along the magnetic field due to thermal velocity. We derive a general dispersion relation taking into account the effects mentioned above and obtain simple expressions for growth rates in limiting cases. Perturbations are shown to have an electromagnetic nature. We find that at conditions under consideration transverse scale sizes of unstable perturbations can have a wide spectrum relatively to longitudinal scale sizes and, in particular, form very thin filaments. The results obtained can be useful for interpretation of observations of dense cold regions in astrophysical objects.

Accepted for publication in MNRAS

References in corpus (8)

• Cold molecular gas in the Perseus cluster core - Association with X-ray cavity, Halpha filaments and cooling flow -
• Anisotropic Thermal Conduction and the Cooling Flow Problem in Galaxy Clusters
• Simulations of MHD Instabilities in Intracluster Medium Including Anisotropic Thermal Conduction
• Electromagnetic streaming instabilities of magnetized accretion disks with strong collisional coupling of species
• Radiation-condensation instability in a four-fluid dusty plasma
• Extraordinary increase of lifetime of localized cold clouds by the viscous effect in thermally-unstable two-phase interstellar media
• Multicomponent theory of buoyancy instabilities in magnetized plasmas: The case of magnetic field parallel to gravity
• Multicomponent theory of buoyancy instabilities in astrophysical plasma objects: The case of magnetic field perpendicular to gravity

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