Simulating X-ray bursts during a transient accretion event
Thermonuclear burst modelling has to date focused on stable accretion rates, but bursts are also observed during episodes of transient accretion. The accretion-powered millisecond pulsar SAX J1808.4—3658 exhibited four helium-rich X-ray bursts during the outburst of 2002 October. Monash student Zac Johnston undertook the first multizone simulations of X-ray bursts throughout the outburst, incorporating a time-varying accretion rate, to try to match the observations. The model, with an accreted hydrogen fraction of X = 0.44 and a CNO metallicity of 0.02, reproduces the observed burst arrival times and fluences well, and offers the prospects of more detailed future simulations of such outbursts. Zac's paper reporting the modeling has now been accepted by MNRAS.
Read the paper arXiv:1711.03970