Magnetic Rayleigh-Taylor Instability in Radiative Flows

TL;DR

This paper analyzes the impact of magnetic fields on the radiative Rayleigh-Taylor instability in astrophysical flows, revealing how magnetic fields can stabilize certain perturbations and significantly alter growth rates in different optical regimes.

Contribution

It provides a linear analysis of the magnetic radiative RT instability in both optically thin and thick regimes, extending understanding of magnetic stabilization effects in astrophysical contexts.

Findings

Magnetic fields stabilize short-wavelength perturbations in optically thin flows.

Growth rates at long wavelengths are reduced by magnetic fields in optically thin regimes.

Magnetic fields increase the instability growth time-scale in protostellar bubbles.

Abstract

We present a linear analysis of the radiative Rayleigh-Taylor (RT) instability in the presence of magnetic field for both optically thin and thick regimes. When the flow is optically thin, magnetic field not only stabilizes perturbations with short wavelengths, but also growth rate of the instability at long wavelengths is reduced compared to a nonmagnetized case. Then, we extend our analysis to the optically thick flows with a conserved total specific entropy and properties of the unstable perturbations are investigated in detail. Growth rate of the instability at short wavelengths is suppressed due to the presence of the magnetic field, however, growth rate is nearly constant at long wavelengths because of the radiation field. Since the radiative bubbles around massive protostars are subject to the RT instability, we also explore implications of our results in this context. In the nonmagnetized case, the growth time-scale of the instability for a typical bubble is found less than one thousand years which is very short compared to the typical star formation time-scale. Magnetic field with a reasonable strength significantly increases the growth time-scale to more than hundreds of thousands years. The instability, furthermore, is more efficient at large wavelengths, whereas in the non-magnetized case, growth rate at short wavelengths is more significant.