Efficiency Crisis of Swift Gamma-Ray Bursts with Shallow X-ray Afterglows : Prior Activity or Time-Dependent Microphysics?
Astronomy and Astrophysics Volume 458 Issue 1
Page 7-12
published_at 2006-10
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| File | |
| Title ( eng ) |
Efficiency Crisis of Swift Gamma-Ray Bursts with Shallow X-ray Afterglows : Prior Activity or Time-Dependent Microphysics?
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| Creator |
Ioka Kunihito
Toma Kenji
Yamazaki Ryo
Nakamura Takashi
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| Source Title |
Astronomy and Astrophysics
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| Volume | 458 |
| Issue | 1 |
| Start Page | 7 |
| End Page | 12 |
| Abstract |
Most X-ray afterglows of gamma-ray bursts (GRBs) observed by the Swift satellite have a shallow decay phase t-1/2 in the first thousands of seconds. We discuss that the shallow decay requires an unreasonably high gamma-ray efficiency, 75-90%, within current models, which is difficult to be produced by internal shocks. Such a crisis may be avoided if a weak relativistic explosion occurs ～ 103-106 s prior to the main burst or if the energy fraction that goes into electrons increases during the shallow decay, e t1/2. The former model predicts a very long precursor while either model would prefer dim optical flashes from the reverse shock as recently reported.
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| NDC |
Astronomy. Space sciences [ 440 ]
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| Language |
eng
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| Resource Type | journal article |
| Publisher |
EDP Sciences
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| Date of Issued | 2006-10 |
| Publish Type | Author’s Original |
| Access Rights | open access |
| Source Identifier |
[ISSN] 0004-6361
[DOI] 10.1051/0004-6361:20064939
[NCID] AA00553195
[DOI] http://dx.doi.org/10.1051/0004-6361:20064939
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