Long optical plateau in the afterglow of the short GRB 150424A with extended emission. Evidence for energy injection by a magnetar?

DOI: 
10.1051/0004-6361/201730578
Publication date: 
01/11/2017
Main author: 
Knust, F.
IAA authors: 
Kann, D. A.
Authors: 
Knust, F.;Greiner, J.;van Eerten, H. J.;Schady, P.;Kann, D. A.;Chen, T. -W.;Delvaux, C.;Graham, J. F.;Klose, S.;Krühler, T.;McConnell, N. J.;Nicuesa Guelbenzu, A.;Perley, D. A.;Schmidl, S.;Schweyer, T.;Tanga, M.;Varela, K.
Journal: 
Astronomy and Astrophysics
Refereed: 
Yes
Publication type: 
Article
Volume: 
607
Pages: 
A84
Abstract: 

Context. Short-duration gamma-ray bursts (GRBs) with extended emission form a subclass of short GRBs, comprising about 15% of the short-duration sample. Afterglow detections of short GRBs are also rare (about 30%) because of their lower luminosity. <BR /> Aims: We present a multiband data set of the short burst with extended emission, GRB 150424A, comprising of GROND observations, complemented with data from Swift/UVOT, Swift/XRT, HST, Keck/LRIS, and data points from the literature. The GRB 150424A afterglow shows an extended plateau phase, lasting about 8 h. The analysis of this unique GRB afterglow might shed light on the understanding of afterglow plateau emission, the nature of which is still under debate. <BR /> Methods: We present a phenomenological analysis made by applying fireball closure relations and interpret the findings in the context of the fireball model. We discuss the plausibility of a magnetar as a central engine, which would be responsible for additional and prolonged energy injection into the fireball. <BR /> Results: We find convincing evidence for energy injection into the afterglow of GRB 150424A. We find that a magnetar spin-down as the source for a prolonged energy injection requires that at least 4% of the spin-down energy is converted into radiation.

Database: 
ADS
SCOPUS
URL: 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034838101&doi=10.1051%2f0004-6361%2f201730578&partnerID=40&md5=c764558f3a900a0c9ee2ba37e8545cbe
ADS Bibcode: 
2017A&A...607A..84K
Keywords: 
gamma-ray burst: general;gamma-ray burst: individual: 150424A;methods: observational;methods: data analysis