Constraining neutron-star properties with ensembles of thermonuclear bursts: accompanying code, data tables, and posterior samples

This dataset is intended to accompany the paper "Constraining neutron-star properties with ensembles of thermonuclear bursts: application to SRGA J144459.2−604207" by Duncan K. Galloway et al., submitted to the Publications of the Astronomical Society of Australia The dataset comprises software, data files, and analysis results: The beans_2.76.1.zip file contains a snapshot of the code used to generate the model results The .ini files allow recreation of the runs described in Table 2 of the paper, as input to the BEANSP code The .p files contain pickled samples from the main runs presented in the paper, labeled by the run_id as listed in Table 2 The paper abstract is copied below Deducing the properties of the host neutron stars from thermonuclear (type-I) X-ray bursts remains a challenge, due to incomplete data, the large (multidimensional) parameter space, and dearth of suitable models and analysis tools. Here we describe further development of the BEANSP package, used previously to analyse several burst samples. We present a new “ensemble” analysis mode, utilising the consistent and regular “clocked” bursting exhibited by some sources, that compares model predictions to epoch averages instead of individual events. This mode requires only one model evaluation per epoch, and so is much more efficient that the previous “train” mode. We apply the code to the best-known source exhibiting “clocked” bursting, GS 1826−24, utilising a grid of KEPLER models pre-calculated for this purpose, and find good agreement with a previous study. We performed a number of experiments on simulated data, demonstrating that we can recover input parameters related to the burst ignition with reasonable accuracy, but less so for the system distance, emission anisotropy and neutron star mass and radius. Finally, we assembled a set of 14 daily burst epochs covering the 2024 outburst of the accretion-powered millisecond pulsar SRGA J144459.2−604207, and attempted to constrain the system properties of this object by comparing to SETTLE model predictions. We find reasonably good agreement between the observations and model predictions for a mildly sub-solar fuel composition, with H-fraction X ≃0.54 and CNO metallicity Z_CNO ≃0.01. However, we note that the inferred H-fraction is in excess of the limit of 0.4 established separately, and the adopted model may not provide sufficiently accurate predictions for this burst ignition regime. The inferred distance depends on assumptions about the system inclination and corresponding anisotropy of the persistent emission, and is likely in the range 6–11 kpc. Future applications with more physically realistic models are a promising avenue for this and other sources with H-rich bursts.