Unveiling the population of orphan γ -ray bursts

  title={Unveiling the population of orphan $\gamma$ -ray bursts},
  author={Giancarlo Ghirlanda and Ruben Salvaterra and Sergio Campana and Susanna D. Vergani and J. Japelj and Maria Grazia Bernardini and Davide Burlon and Paolo D’Avanzo and A. Melandri and A Gomboc and Francesco Nappo and Roberta Paladini and Alessio Pescalli and Om Sharan Salafia and Gianpiero Tagliaferri},
  journal={Astronomy and Astrophysics},
Gamma-ray bursts (GRBs) are detectable in the γ-ray band if their jets are oriented toward the observer. However, for each GRB with a typical θ_(jet), there should be ~2/θ^2_(jet) bursts whose emission cone is oriented elsewhere in space. These off-axis bursts can eventually be detected when, due to the deceleration of their relativistic jets, the beaming angle becomes comparable to the viewing angle. Orphan afterglows (OAs) should outnumber the current population of bursts detected in the… 

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