| A comprehensive analysis of swift XRT data. II. Diverse physical origins of the shallow decay segment | |
Liang, EW1,2; Zhang BB(张彬彬)1,3 ; Zhang, B1; Liang, EW (reprint author), Univ Nevada, Dept Phys & Astron, Las Vegas, NV 89154 USA.
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| 发表期刊 | ASTROPHYSICAL JOURNAL
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| 2007-11-20 | |
| 卷号 | 670期号:1页码:565-583 |
| DOI | 10.1086/521870 |
| 产权排序 | 第3完成单位 |
| 收录类别 | SCI |
| 关键词 | Gamma Rays : Bursts Radiation Mechanisms : Nonthermal X-rays : General |
| 摘要 | The origin of the shallow decay segment in Swift XRT light curves remains a puzzle. We analyze the properties of this segment with a sample of 53 long Swift GRBs detected before 2007 February. We show that the distributions of the sample's characteristics are lognormal or normal, and its isotropic X-ray energy (E(iso),X) is linearly correlated with the prompt gamma-ray energy but with a steeper photon spectrum, aside from some X-ray flashes. No significant spectral evolution is observed from this phase to the following phase, and the latter is usually consistent with external shock models, implying that the shallow decay is also of external-shock origin, likely a refreshed external shock. Within the refreshed-shock model, the data are generally consistent with a roughly constant injection luminosity up to the end of this phase, t(b). A positive correlation between Eiso; X and tb also favors this scenario. Among the 13 bursts that have well-sampled optical light curves, six have an optical break around tb and the breaks are consistent with being achromatic. However, the other seven either do not show an optical break or have a break at an epoch different from tb. This raises a concern for the energy injection scenario, suggesting that the optical and X-ray emission may not be the same component, at least for some bursts. There are four significant outliers in the sample, GRBs 060413, 060522, 060607A, and 070110. The shallow decay phase in these bursts is immediately followed by a very steep decay after tb, which is inconsistent with any external-shock model. The optical data for these bursts evolve independently from the X-ray data. These X-ray plateaus likely have an internal origin and demand continuous operation of a long-term central engine. We conclude that the observed shallow decay phase likely has diverse physical origins. |
| 语种 | 英语 |
| 学科领域 | Astronomy & Astrophysics |
| 文章类型 | Review |
| ISSN | 0004-637X |
| URL | 查看原文 |
| WOS记录号 | WOS:000250965400042 |
| WOS研究方向 | Astronomy & Astrophysics |
| WOS类目 | Astronomy & Astrophysics |
| 关键词[WOS] | GAMMA-RAY BURST ; AFTERGLOW LIGHT CURVES ; CONTINUOUS ENERGY INJECTION ; RELATIVISTIC WIND BUBBLES ; OPTICAL OBSERVATIONS ; MILLISECOND PULSARS ; THEORETICAL IMPLICATIONS ; SPECTRAL EVOLUTION ; LORENTZ FACTOR ; BLACK-HOLES |
| 引用统计 | |
| 文献类型 | 期刊论文 |
| 条目标识符 | http://ir.ynao.ac.cn/handle/114a53/7016 |
| 专题 | 星系研究组 |
| 通讯作者 | Liang, EW (reprint author), Univ Nevada, Dept Phys & Astron, Las Vegas, NV 89154 USA. |
| 作者单位 | 1.Department of Physics and Astronomy, University of Nevada, Las Vegas, Las Vegas, NV 89154 2.Department of Physics, Guangxi University, Nanning, 530004 Guangxi, China 3.National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences, Kunming, 650011 Yunnan, China |
| 推荐引用方式 GB/T 7714 | Liang, EW,Zhang BB,Zhang, B,et al. A comprehensive analysis of swift XRT data. II. Diverse physical origins of the shallow decay segment[J]. ASTROPHYSICAL JOURNAL,2007,670(1):565-583. |
| APA | Liang, EW,Zhang BB,Zhang, B,&Liang, EW .(2007).A comprehensive analysis of swift XRT data. II. Diverse physical origins of the shallow decay segment.ASTROPHYSICAL JOURNAL,670(1),565-583. |
| MLA | Liang, EW,et al."A comprehensive analysis of swift XRT data. II. Diverse physical origins of the shallow decay segment".ASTROPHYSICAL JOURNAL 670.1(2007):565-583. |
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