Inferring properties of neutron stars born in short gamma-ray bursts with a plerion-like X-ray plateau
Using a plerion-like model to infer neutron star properties of short gamma-ray bursts with an X-ray plateau
In Strang & Melatos (2019), we developed a simple model for a millisecond magnetar central engine to drive X-ray afterglows from short gamma-ray bursts (sGRBs) based on early models of young supernova remnants. In this work, we use the afterglows of six sGRBs to infer the properties of the source neutron star.
Citation
L. C. Strang, A. Melatos, N. Sarin, P. D. Lasky, Inferring properties of neutron stars born in short gamma-ray bursts with a plerion-like X-ray plateau, MNRAS, accepted, arxiv.org/abs/2107.13787
Abstract
Time-resolved spectra of six short gamma-ray bursts (sGRBs), measured by the {\em Swift} telescope, are used to estimate the parameters of a plerion-like model of the X-ray afterglow. The unshrouded, optically thin component of the afterglow is modelled as emanating from an expanding bubble of relativistic, shock-accelerated electrons fuelled by a central object. The electrons are injected with a power-law distribution and cool mainly by synchrotron losses. We compute posteriors for model parameters describing the central engine (e.g. spin frequency at birth, magnetic field strength) and shock acceleration (e.g. power-law index, minimum injection energy). It is found that the central engine is compatible with a millisecond magnetar, and the shock physics is compatible with what occurs in Galactic supernova remnants, assuming standard magnetic field models for the magnetar wind. Separately, we allow the magnetic field to vary arbitrarily and infer that it is roughly constant and lower in magnitude than the wind-borne extension of the inferred magnetar field. This may be due to the expansion history of the bubble, or the magnetization of the circumstellar environment of the sGRB progenitor.
Overview
Acknowledgements
All scientific acknowledgements can be found in the reference section of the paper. The following additional resources were used on this page:
- Data
- This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester.
- Evans et al. (2007, A&A, 469, 379)
- Evans et al. (2009, MNRAS, 397, 1177)
