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Title: Fallback accretion on to a newborn magnetar: short GRBs with extended emission
Authors: Gibson, S. L.
Wynn, G. A.
Gompertz, B. P.
O'Brien, Paul Thomas
First Published: 17-Jun-2017
Publisher: Oxford University Press
Citation: Monthly Notices of the Royal Astronomical Society, 2017, 470 (4), pp. 4925-4940
Abstract: 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.
DOI Link: 10.1093/mnras/stx1531
ISSN: 0035-8711
eISSN: 1365-2966
Version: Publisher Version
Status: Peer-reviewed
Type: Journal Article
Rights: Copyright © 2017, The Author(s). Deposited with reference to the publisher’s open access archiving policy.
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

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