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Fallback accretion on to a newborn magnetar: short GRBs with extended emission

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journal contribution
posted on 12.03.2018, 12:35 by S. L. Gibson, G. A. Wynn, B. P. Gompertz, Paul Thomas O'Brien
There is a subset of short gamma-ray bursts (SGRBs) that exhibit a rebrightening in their high-energy light curves known as extended emission. These bursts have the potential to discern between various models proposed to describe SGRBs as any model needs to account for extended emission. In this paper, we combine fallback accretion into the magnetar propeller model and investigate the morphological changes fallback accretion has on model light curves and fit to the afterglows of 15 SGRBs exhibiting extended emission from the Swift archive. We have parametrized the fallback in terms of existing parameters within the propeller model and solved for the disc mass and angular frequency of the magnetar over time. We then apply a Markov chain Monte Carlo routine to produce fits to the data. We present fits to our extended emission SGRB sample that are morphologically and energetically consistent with the data provided by Swift Burst Alert Telescope and X-ray Telescope. The parameters derived from these fits are consistent with predictions for magnetar properties and fallback accretion models. Fallback accretion provides a noticeable improvement to the fits of the light curves of SGRBs with extended emission when compared to previous work and could play an important role in explaining features such as variability, flares and long dipole plateaux.

History

Citation

Monthly Notices of the Royal Astronomical Society, 2017, 470 (4), pp. 4925-4940

Author affiliation

/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy

Version

VoR (Version of Record)

Published in

Monthly Notices of the Royal Astronomical Society

Publisher

Oxford University Press

issn

0035-8711

eissn

1365-2966

Acceptance date

14/06/2017

Copyright date

2017

Available date

12/03/2018

Publisher version

https://academic.oup.com/mnras/article/470/4/4925/3869630

Language

en