• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>The Astrophysical journal >A SEARCH FOR DISCRETE X-RAY SPECTRAL FEATURES IN A SAMPLE OF BRIGHT γ-RAY BURST AFTERGLOWS
【24h】

A SEARCH FOR DISCRETE X-RAY SPECTRAL FEATURES IN A SAMPLE OF BRIGHT γ-RAY BURST AFTERGLOWS

机译：明亮的γ射线爆炸后样品中离散X射线光谱特征的搜索

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

We present uniform, detailed spectral analyses of γ-ray burst (GRB) X-ray afterglows observed with ASCA, BeppoSAX, Chandra, and XMM-Newton and critically evaluate the statistical significances of X-ray emission and absorption features in these spectra. The sample consists of 21 X-ray afterglow observations up to and including that of GRB 040106 with spectra of sufficient statistical quality to allow meaningful line searches, chosen here somewhat arbitrarily to be detections with more than 100 total (source plus background) counts. This sample includes all nine X-ray afterglows with published claims of line detections. Moderate resolution spectra are available for 16 of the 21 sources and for the remaining five the Chandra transmission grating spectrometers obtained high-resolution data. All of the data are available from the public archive. We test a simple hypothesis in which the observed spectra are produced by a power-law continuum model modified by photoelectric absorption by neutral material both in our Galaxy and possibly also local to the burst. As a sample, these afterglow spectra are consistent with this relatively simple model. However, since the x~2 statistic is not sensitive to weak and/or localized fluctuations, we have performed Monte Carlo simulations to search for discrete features and to estimate their significances. Our analysis shows that there are four afterglows (GRB 011211, GRB 030227, GRB 021004, and GRB 040106) with line-like features that are significant at the 3 σ level. We cautiously note that, in two cases, the features are associated with an unusual background feature; in the other two, the fractional magnitudes of the lines are small, and comparable to the expected level of systematic uncertainty in the spectral response. In addition, none of the statistically significant features are seen in more than one detector or spectral order where available. We conclude that, to date, no credible X-ray line feature has been detected in a GRB afterglow. Finally, in a majority of cases, we find no evidence for significant absorbing columns local to the GRB host galaxy, implying that there is little evidence from X-ray observations that GRB preferentially explode in high-density environments.
机译：我们提供用ASCA，BeppoSAX，Chandra和XMM-Newton观测到的γ射线爆裂（GRB）X射线余辉的统一，详细的光谱分析，并严格评估这些光谱中X射线发射和吸收特征的统计意义。该样品包括21个X射线余辉观测值，直至GRB 040106，包括GRB 040106，其光谱质量也足以进行有意义的线搜索，在此可以任意选择以进行总计100个以上（源加背景）计数的检测。该样本包括所有九种X射线余辉，并公开了有关线检测的声明。 21种光源中的16种可获得中等分辨率的光谱，其余5种Chandra透射光栅光谱仪可获得高分辨率的数据。所有数据都可以从公共档案中获得。我们测试了一个简单的假设，在该假设中，观察到的光谱是由幂定律连续模型产生的，该幂定律连续模型通过我们银河系中以及可能也位于爆发区域的中性材料的光电吸收进行了修改。作为样本，这些余辉光谱与此相对简单的模型一致。但是，由于x〜2统计量对微弱和/或局部波动不敏感，因此我们执行了蒙特卡罗模拟来搜索离散特征并估计其重要性。我们的分析显示，有四个余辉（GRB 011211，GRB 030227，GRB 021004和GRB 040106）具有类似线状的特征，且在3σ水平上很显着。我们谨慎地注意到，在两种情况下，这些功能与异常的背景功能相关;在另外两个中，线的分数幅度很小，可以与光谱响应中系统不确定性的预期水平相媲美。另外，在可用的情况下，在不止一个检测器或频谱顺序中看不到统计上显着的特征。我们得出的结论是，迄今为止，尚未在GRB余辉中检测到可靠的X射线线特征。最后，在大多数情况下，我们没有发现GRB宿主星系局部存在明显的吸收柱的证据，这意味着从X射线观测结果来看，几乎没有证据表明GRB在高密度环境中优先爆炸。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号