| THE BULK LORENTZ FACTORS OF FERMI-LAT GAMMA RAY BURSTS | |
Zhao XH(赵晓红)1,2 ; Li, Z3,4; Bai JM(白金明)1,2; Zhao, XH (reprint author), Chinese Acad Sci, Yunnan Observ, Natl Astron Observ, POB 110, Kunming 650011, Peoples R China.
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| 发表期刊 | ASTROPHYSICAL JOURNAL
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| 2011-01-10 | |
| 卷号 | 726期号:2页码:89-96 |
| DOI | 10.1088/0004-637X/726/2/89 |
| 产权排序 | 第1完成单位 |
| 收录类别 | SCI |
| 关键词 | Gamma-ray Burst: General |
| 摘要 | The Lorentz factor (LF) of gamma-ray burst (GRB) ejecta may be constrained by observations of high-energy (HE) spectral attenuation. The recent Fermi-LAT observations of prompt GeV emission from several bright GRBs have led to conclusions of unexpectedly large LFs, Gamma > 10(3). Here we revisit this problem with two main concerns. (1) With a one-zone assumption where all photons are assumed to be generated in the same region (radius) and time, we self-consistently calculate the gamma gamma optical depth by adopting a target photon spectrum with an HE cutoff. We find that this might be important when the GRB LF is below a few hundreds. (2) Recent Fermi-LAT observations suggest that the bulkMeV-range and HE (greater than or similar to 100 MeV) emission may arise from different regions. We then consider a two-zone case where HE emission is generated in much larger radii than that of the MeV-range emission. We find that the HE emission may mainly be attenuated by the MeV-range emission and that the attenuated HE spectrum does not show an exponential spectral cutoff but a slight steepening. This suggests that there may be no abrupt cutoff due to gamma gamma attenuation if relaxing the one-zone assumption. By studying the spectra of three bright Fermi-LAT GRBs, 080916C, 090510, and 090902B, we show that bulk LFs of Gamma similar to 600 can be consistent with observations in the two-zone case. Even lower LFs can be obtained in the multi-zone case. |
| 项目资助者 | National Natural Science Foundation of China (NSFC) [10973034, 10843007] ; 973 Program [2009CB824800] ; Foundation for the Authors of National Excellent Doctoral Dissertations of China |
| 语种 | 英语 |
| 学科领域 | Astronomy & Astrophysics |
| 文章类型 | Article |
| ISSN | 0004-637X |
| URL | 查看原文 |
| 归档日期 | 2011-02-21 |
| WOS记录号 | WOS:000285623600033 |
| WOS研究方向 | Astronomy & Astrophysics |
| WOS类目 | Astronomy & Astrophysics |
| 关键词[WOS] | PROMPT OPTICAL-EMISSION ; GRB 080916C ; RESIDUAL COLLISIONS ; AFTERGLOW ; OUTFLOWS ; PHOTONS ; SPECTRA ; ESCAPE ; MOTION |
| 引用统计 | |
| 文献类型 | 期刊论文 |
| 条目标识符 | http://ir.ynao.ac.cn/handle/114a53/5412 |
| 专题 | 南方基地 中国科学院天体结构与演化重点实验室 |
| 通讯作者 | Zhao, XH (reprint author), Chinese Acad Sci, Yunnan Observ, Natl Astron Observ, POB 110, Kunming 650011, Peoples R China. |
| 作者单位 | 1.National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences, P.O. Box 110, 650011 Kunming, China 2.Key Laboratory for the Structure and Evolution of Celestial Bodies, Chinese Academy of Sciences, P.O. Box 110, 650011 Kunming, China 3.Department of Astronomy, Peking University, Beijing 100871, China 4.Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, China |
| 第一作者单位 | 中国科学院云南天文台 |
| 推荐引用方式 GB/T 7714 | Zhao XH,Li, Z,Bai JM,et al. THE BULK LORENTZ FACTORS OF FERMI-LAT GAMMA RAY BURSTS[J]. ASTROPHYSICAL JOURNAL,2011,726(2):89-96. |
| APA | Zhao XH,Li, Z,Bai JM,&Zhao, XH .(2011).THE BULK LORENTZ FACTORS OF FERMI-LAT GAMMA RAY BURSTS.ASTROPHYSICAL JOURNAL,726(2),89-96. |
| MLA | Zhao XH,et al."THE BULK LORENTZ FACTORS OF FERMI-LAT GAMMA RAY BURSTS".ASTROPHYSICAL JOURNAL 726.2(2011):89-96. |
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| THE BULK LORENTZ FAC（614KB） | 期刊论文 | 作者接受稿 | 开放获取 | CC BY-NC-SA | 浏览 请求全文 | |
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