Three-dimensional instability of flame fronts in type I X-ray bursts

Abstract

We present the first realistic 3D simulations of flame front instabilities during type I X-ray bursts. The unperturbed front is characterised by the balance between the pressure gradient and the Coriolis force of a spinning neutron star (ν = 450 Hz in our case). This balance leads to a fast horizontal velocity field parallel to the flame front. This flow is strongly sheared in the vertical direction. When we perturb the front an instability quickly corrugates the front. We identify this instability as the baroclinic instability. Most importantly, the flame is not disrupted by the instability and there are two major consequences: the overall flame propagation speed is {\sim} 10 times faster than in the unperturbed case and distinct flame vortices appear. The speedup is due to the corrugation of the front and the dynamics of the vortices. These vortices may also be linked to the oscillations observed in the lightcurves of the bursts.

References in corpus (18)

• Thermonuclear (type-I) X-ray bursts observed by the Rossi X-ray Timing Explorer
• Nuclear-Powered Millisecond Pulsars and the Maximum Spin Frequency of Neutron Stars
• Thermonuclear burst oscillations
• Propagation of thermonuclear flames on rapidly rotating neutron stars: extreme weather during type I X-ray bursts
• eXTP -- enhanced X-ray Timing and Polarimetry Mission
• Rotational Evolution During Type I X-Ray Bursts
• R-Modes on Rapidly Rotating, Relativistic Stars: I. Do Type-I Bursts Excite Modes in the Neutron-Star Ocean?
• Magnetohydrodynamic Shallow Water Waves: Linear Analysis
• Flame Propagation on the Surfaces of Rapidly Rotating Neutron Stars during Type I X-ray Bursts
• Multidimensional Modeling of Type I X-ray Bursts. I. Two-Dimensional Convection Prior to the Outburst of a Pure Helium Accretor
• Rotational effects in thermonuclear Type I Bursts: equatorial crossing and directionality of flame spreading
• Neutron Star Crustal Interface Waves
• Fast and slow magnetic deflagration fronts in Type I X-ray bursts
• Evolution of the bursting-layer wave during a Type 1 X-ray burst
• Latitudinal Shear Instabilities during Type I X-ray Bursts
• On the dependence of X-ray burst rate on accretion and spin rate
• Burning in the tail: implications for a burst oscillation model
• A numerical magnetohydrodynamic scheme using the hydrostatic approximation

Cited by in corpus (10)

• Discovery of a thermonuclear Type I X-ray burst in infrared: new limits on the orbital period of 4U 1728-34
• The efficiency of nuclear burning during thermonuclear (Type I) bursts as a function of accretion rate
• Relativistic ocean $r$-modes during type-I X-ray bursts
• Nuclear-powered X-ray millisecond pulsars
• Dynamics of Laterally Propagating Flames in X-ray Bursts. I. Burning Front Structure
• Pulse Profile Modeling of Thermonuclear Burst Oscillations I: The Effect of Neglecting Variability
• The Peculiar Behavior of Burst Oscillations in the Accreting Millisecond X-ray Pulsar XTE J1814-338
• Comparing Early Evolution of Flames in X-ray Bursts in Two and Three Dimensions
• Simulating Lateral H/He Flame Propagation in Type I X-ray Bursts
• Discovery of burst oscillations in the newly discovered millisecond X-ray pulsar SRGA J144459.2$-$604207