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

A. Cucchiara, P. Veres, A. Corsi, S. B. Cenko, D. A. Perley, A. Lien, F. E. Marshall, C. Pagani, V. L. Toy, J. I. Capone, D. A. Frail, A. Horesh, M. Modjaz, N. R. Butler, O. M. Littlejohns, A. M. Watson, A. S. Kutyrev, W. H. Lee, M. G. Richer, C. R. KleinO. D. Fox, J. X. Prochaska, J. S. Bloom, E. Troja, E. Ramirez-Ruiz, J. A. De Diego, L. Georgiev, J. González, C. G. Román-Zñiga, N. Gehrels, H. Moseley

    Research output: Contribution to journalArticlepeer-review

    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.

    Original languageEnglish (US)
    Article number122
    JournalAstrophysical Journal
    Volume812
    Issue number2
    DOIs
    StatePublished - Oct 20 2015

    Keywords

    • gamma-ray burst: general
    • gamma-ray burst: individual (GRB 141121A)

    ASJC Scopus subject areas

    • Nuclear and High Energy Physics

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