Rayleigh-Taylor Instability at Ionization Fronts: Perturbation Analysis

Abstract

The linear growth rate of the Rayleigh-Taylor instability (RTI) at ionization fronts is investigated via perturbation analysis in the limit of incompressible fluids. In agreement with previous numerical studies is found that absorption of ionizing radiation inside the HII region due to hydrogen recombinations suppresses the growth of instabilities. In the limit of a large density contrast at the ionization front the RTI growth rate has the simple analytical solution n=-nur+(nur^2+gk)^(1/2), where nur is the hydrogen recombination rate inside the HII region, k is the perturbation's wavenumber and g is the effective acceleration in the frame of reference of the front. Therefore, the growth of surface perturbations with wavelengths lambda >> lambda_{cr} = 2πg/nur^2 is suppressed by a factor (lambda_{cr}/4lambda)^(1/2) with respect to the non-radiative incompressible RTI. Implications on stellar and black hole feedback are briefly discussed.

Accepted for publication in MNRAS. 9 pages

References in corpus (5)

• The Magnetic Rayleigh-Taylor Instability in Three Dimensions
• Three-Dimensional Dynamical Instabilities in Galactic Ionization Fronts
• Non-linear Evolution of Rayleigh-Taylor Instability in a Radiation Supported Atmosphere
• Rayleigh-Taylor instability of ionization front around black holes
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