Buoyancy Instabilities in Weakly Magnetized Low-Collisionality Plasmas
By E. Quataert. 2007
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I calculate the linear stability of a stratified low-collisionality plasma in the presence of a weak magnetic field. Heat is assumed to flow only along magnetic field lines. In the absence of a heat flux in the background plasma, Balbus demonstrated that plasmas in which the temperature increases in the direction of gravity are buoyantly unstable to convective-like motions (the “magnetothermal instability”). I show that in the presence of a background heat flux, an analogous instability is present when the temperature decreases in the direction of gravity. The instability is driven by the background heat flux, and the fastest growing mode has a growth time of order the local dynamical time. Thus, independent of the sign of the temperature gradient, weakly magnetized low-collisionality plasmas are unstable on a dynamical time to magnetically mediated buoyancy instabilities. The instability described in this paper is predicted to be present in clusters of galaxies at radii ~0.1-100 kpc, where the observed temperature increases outward. Possible consequences for the origin of cluster magnetic fields, “cooling flows,” and the thermodynamics of the intercluster medium are briefly discussed.
Subfields: Astronomy and Astrophysics
View Paper: https://www.semanticscholar.org/paper/d1c796ad22185b928fee319146a5bd90d88e2b32
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In Astronomy and Astrophysics
Citations in the corpus
- Mechanical feedback from active galactic nuclei in galaxies, groups and clusters (2012, background): “With a positive radial temperature gradient, highly anisotropic conduction makes an atmosphere subject to the heat flux driven buoyancy instability (HBI, Quataert 2008).”
- The impact of star formation feedback on the circumgalactic medium (2016, background): “Magnetic fields, (anisotropic) conduction (Balbus 2001; Quataert 2008; McCourt et al. 2011), viscosity (Kunz 2011; Parrish et al. 2012), and cosmic rays (Booth et al. 2013) may be important for properly modeling the CGM.”
- INTRACLUSTER MEDIUM ENTROPY PROFILES FOR A CHANDRA ARCHIVAL SAMPLE OF GALAXY CLUSTERS (2009, background): “More specifically, how magnetohydrodynamic instabilities, such as MTI (Balbus 2000; Quataert 2008) and HBI (Parrish & Quataert 2008), might impact the entropy structure of the ICM and formation of thermal instabilities needs to be investigated more thoroughly.”
- A Global Model for Circumgalactic and Cluster-core Precipitation (2016, background): “Cosmological MHD simulations will also be needed to clarify whether the magnetothermal instability (Balbus 1991) or heat-flux driven buoyancy instability (Quataert 2008; Parrish & Quataert 2008) alter the general picture of susceptibility to condensation that we have outlined here.”
- Jet-regulated cooling catastrophe (2010, background): “In particular, recent efforts have been made to investigate the importance of anisotropic thermal conduction in idealized galaxy clusters (Parrish & Quataert 2008; Parrish et al. 2009; Bogdanović et al. 2009).”
- Massive and refined - II. The statistical properties of turbulent motions in massive galaxy clusters with high spatial resolution (2010, background): “…et al.2010, Morsony et al.2010; Vazza 2010), while the interplay of tan-gled magnetic field and Cosmic Rays is expected to inject chaotic motions at very small scales, via instabilites in the ICM (Parrish & Stone 2008; Quataert 2008; Ruskowsky & Oh 2010; McCourt et al.2010; Ruszkowsky et al.2010).”
- An origin for multiphase gas in galactic winds and haloes (2015, background): “However, because all of the gas ultimately cools to PIE in our fiducial models at ∼ 103−104 K there is nothing to maintain pressure equilibrium for convective instability criterion in dilute plasma such as the galactic winds of interest here (Quataert 2008).”