IPTF14yb: The first discovery of a gamma-ray burst afterglow independent of a high-energy trigger

S. Bradley Cenko, Alex L. Urban, Daniel A. Perley, Assaf Horesh, Alessandra Corsi, Derek B. Fox, Yi Cao, Mansi M. Kasliwal, Amy Lien, Iair Arcavi, Joshua S. Bloom, Nat R. Butler, Antonino Cucchiara, José A.De Diego, Alexei V. Filippenko, Avishay Gal-Yam, Neil Gehrels, Leonid Georgiev, J. Jesús González, John F. GrahamJochen Greiner, D. Alexander Kann, Christopher R. Klein, Fabian Knust, S. R. Kulkarni, Alexander Kutyrev, Russ Laher, William H. Lee, Peter E. Nugent, J. Xavier Prochaska, Enrico Ramirez-Ruiz, Michael G. Richer, Adam Rubin, Yuji Urata, Karla Varela, Alan M. Watson, Przemek R. Wozniak

Research output: Contribution to journalArticlepeer-review

49 Scopus citations


We report here the discovery by the Intermediate Palomar Transient Factory (iPTF) of iPTF14yb, a luminous(Mr ≈ -27.8 mag), cosmological (redshift 1.9733), rapidly fading optical transient. We demonstrate, based onprobabilistic arguments and a comparison with the broader population, that iPTF14yb is the optical afterglow ofthe long-duration gamma-ray burst GRB 140226A. This marks the first unambiguous discovery of a GRBafterglow prior to (and thus entirely independent of) an associated high-energy trigger. We estimate the rate ofiPTF14yb-like sources (i.e., cosmologically distant relativistic explosions) based on iPTF observations, inferringan all-sky value of Rrel = 610 yr?1 (68% confidence interval of 1102000 yr?1). Our derived rate is consistent(within the large uncertainty) with the all-sky rate of on-axis GRBs derived by the Swift satellite. Finally, webriefly discuss the implications of the nondetection to date of bona fide orphan afterglows (i.e., those lackingdetectable high-energy emission) on GRB beaming and the degree of baryon loading in these relativistic jets.

Original languageEnglish (US)
Article numberL24
JournalAstrophysical Journal Letters
Issue number2
StatePublished - Apr 20 2015

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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