Orphan GRB Afterglow Searches with the Pan-STARRS1 COSMOS Survey

Yun Jing Huang, Yuji Urata, Kuiyun Huang, Kuei Sheng Lee, Meng Feng Tsai, Yuji Shirasaki, Marcin Sawicki, Stephane Arnouts, Thibaud Moutard, Stephen Gwyn, Wei Hao Wang, Sebastien Foucaud, Keiichi Asada, Mark E. Huber, Richard Wainscoat, Kenneth C. Chambers

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9 Scopus citations


We present the result of a search for orphan gamma-ray burst (GRB) afterglows in the Pan-STARRS1 (PS1) COSMOS survey. There is extensive theoretical and observational evidence suggesting that GRBs are collimated jets; the direct observation of orphan GRB afterglows would further support this model. An optimal survey strategy is designed by coupling the PS1 survey with the Subaru/Hyper-Suprime-Cam (HSC) survey. The PS1 COSMOS survey, one of the survey fields in the PS1 Medium Deep Survey (PS1/MDS), searches a field of 7 deg2 from 2011 December to 2014 January, reaching a limiting magnitude R ∼ 23. The dense cadence of PS1/MDS is crucial for identifying transients, and the deep magnitude reached by the HSC survey (R ∼ 26) is important for evaluating potential GRB hosts. A transient classification method is employed to select potential orphan GRB afterglow candidates. After a thorough analysis of the transient and host galaxy properties, we conclude that there are no candidates in this survey field. The null result implies that the consideration of jet structures is essential for further orphan GRB afterglow surveys.

Original languageEnglish
Article number69
JournalAstrophysical Journal
Issue number1
StatePublished - 1 Jul 2020


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