2017 JINA-CEE Frontiers in Nuclear Astrophysics

The first simulations of X-ray bursts during a time-variable accretion event

8 Feb 2017, 11:45

15m

Radisson Hotel Lansing

Talk [Main Conference] Contributed talk Session 6

Speaker

Mr Zac Johnston (Monash Centre for Astrophysics, Monash University)

Description

Type I X-ray bursts are periodic flares from the surface of accreting neutron stars, triggered when the accreted envelope is compressed to thermonuclear runaway. They can be fuelled by transient accretion outbursts, during which the accretion rate can vary by an order of magnitude in a matter of days. The pulsar SAX J1808.4-3658 exhibits outbursts every 2–3 years, and four helium-rich X-ray bursts were observed during a typical month-long outburst in 2002. We present the first multi-zone simulations of X-ray bursts with time-dependent accretion rates, using the 2002 outburst as a test case. In addition to reproducing the observed burst properties, we find that using an averaged, constant accretion rate systematically overestimates the burst rate.