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| Paper: |
Orphan Afterglows and Gamma Ray Burst Jets |
| Volume: |
312, Third Rome Workshop on Gamma-Ray Bursts in the Afterglow Era |
| Page: |
363 |
| Authors: |
Rhoads, J.E. |
| Abstract: |
Orphan afterglows are transients resembling gamma ray burst afterglows but observed without accompanying γ-ray emission. Such orphans may be produced by collimated gamma ray bursts viewed outside the initial jet, and studying their statistics will allow constraints to be placed on GRB collimation. Orphans may also be produces by on-axis "dirty fireballs," i.e., explosions with peak Lorentz factors too low for synchrotron γ-ray emission but adequate to power afterglow. In this review, I discuss the theoretical basis for orphan afterglow searches and summarize the present observational results. I also discuss ways to distinguish orphans from off-axis jets and those from dirty fireballs. This will ultimately allow orphan afterglow surveys to constrain GRB opening angles, jet angular structure, and the distribution of initial Lorentz factor for cosmological fireballs. |
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