Happy birthday swift: Ultra-long GRB 141121A and its broadband afterglow

Cucchiara, A, Veres, P, Corsi, A, Cenko, SB, Perley, DA, Lien, A, Marshall, FE, Pagani, C, Toy, VL, Capone, JI, Frail, DA, Horesh, A, Modjaz, M, Butler, NR, Littlejohns, OM, Watson, AM, Kutyrev, AS, Lee, WH, Richer, MG, Klein, CR et al (2015) Happy birthday swift: Ultra-long GRB 141121A and its broadband afterglow. The Astrophysical Journal, 812 (2). ISSN 1538-4357

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Abstract

We present our extensive observational campaign on the Swift-discovered GRB 141121A, almost 10 years after its launch. Our observations cover radio through X-rays and extend for more than 30 days after discovery. The prompt phase of GRB 141121A lasted 1410 s and, at the derived redshift of z = 1.469, the isotropic energy is Eγ,iso = 8.0 1052 erg. Due to the long prompt duration, GRB 141121A falls into the recently discovered class of ultra-long GRBs (UL-GRBs). Peculiar features of this burst are (1) a flat early-time optical light curve and (2) a radio-to-X-ray rebrightening around three days after the burst. The latter is followed by a steep optical-to-X-ray decay and a much shallower radio fading. We analyze GRB 141121A in the context of the standard forward-reverse shock (FS, RS) scenario and we disentangle the FS and RS contributions. Finally, we comment on the puzzling early-time (t ≲ 3 days) behavior of GRB 141121A, and suggest that its interpretation may require a two-component jet model. Overall, our analysis confirms that the class of UL-GRBs represents our best opportunity to firmly establish the prominent emission mechanisms in action during powerful gamma-ray burst explosions, and future missions (like SVOM, XTiDE, or ISS-Lobster) will provide many more of such objects.
© 2015. The American Astronomical Society. All rights reserved.

Item Type:	Article
Uncontrolled Keywords:	0201 Astronomical And Space Sciences, 0305 Organic Chemistry, 0306 Physical Chemistry (Incl. Structural)
Subjects:	Q Science > QB Astronomy Q Science > QC Physics Q Science > QD Chemistry
Divisions:	Astrophysics Research Institute
Publisher:	American Astronomical Society
Date of acceptance:	6 August 2015
Date of first compliant Open Access:	21 February 2017
Date Deposited:	21 Feb 2017 09:34
Last Modified:	04 Sep 2021 11:54
DOI or ID number:	10.1088/0004-637X/812/2/122
URI:	https://researchonline.ljmu.ac.uk/id/eprint/5616

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