Almost 20 years ago I made the first attempt to match thermonuclear bursts with the predictions of Andrew Cumming's "settle" code, for the well-known accretion-powered millisecond pulsar SAX J1808.4—3658. The code was written in IDL and kind of clunky, but worked (after a fashion).

Adelle Goodwin took up the reins for her undergrad, and later PhD work, updating both the settle code and translating my crusty IDL code into Python. Over that time we (with Tom Hilder and others) also attempted to apply the code to additional sources, but could never quite get it to work.

With the expert help of the ADACS team, via a project led by Adelle, we have made substantial corrections and improvements to the matching code, now known as beansp (the "p" is silent). In a new paper submitted to MNRAS, we have now successfully applied the code to a second system, IGR J17498—2921. This (also) 401 Hz pulsar went into outburst in 2011 and exhibited a series of bursts, which we matched with settle to infer a very low H-fraction and metallicity. We also constrain the system inclination and find suggestions for a massive (around twice the mass of our sun) neutron star.

Hopefully the code will be applied to additional systems in the near future!

Labels: 2024, thermonuclear bursts