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arXiv 1105.0917astro-ph.HEastro-ph.CO
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关于GRB 081029余辉的极快光学再增亮的性质

On the nature of the extremely fast optical rebrightening of the afterglow of GRB 081029

M. Nardini, J. Greiner, T. Kruehler, R. Filgas, S. Klose, P. Afonso, C. Clemens, A. Nicuesa Guelbenzu, F. Olivares E., A. Rau, A. Rossi, A. Updike, A. Kupcu Yol… 展开作者

M. Nardini, J. Greiner, T. Kruehler, R. Filgas, S. Klose, P. Afonso, C. Clemens, A. Nicuesa Guelbenzu, F. Olivares E., A. Rau, A. Rossi, A. Updike, A. Kupcu Yoldas, A. Yoldas, D. Burlon, J. Elliott, D. A. Kann

摘要:

上下文斯威夫特卫星发射后,伽马射线暴(GRB)的光学光曲线平滑度范例受到质疑,这要归功于更快、更好的采样光学跟踪,它揭示了一个非常复杂的行为。这种复杂性引起了整个GRB社区的兴趣。GROND多通道成像仪用于研究伽马射线暴的光学和近红外(NIR)余辉,具有前所未有的光学和近红外时间和光谱分辨率。GRB 081029有一个非常突出的光学再亮事件,是多通道成像仪应用于GRB余辉的杰出例子。目标。在这里,我们利用丰富的GROND多色后续的GRB 081029结合XRT观测研究的性质,出现在一些GRB余辉的光学近红外光变曲线的后期再亮。方法.我们分析了光学和近红外观测获得的七通道伽马射线暴光学和近红外探测器(GROND)在2.2米MPI/ESO望远镜和X射线数据获得的XRT望远镜上的斯威夫特天文台。在不同的物理模型框架下讨论了多波长的时间和光谱演化。结果在GRB 081029中观察到的极其陡峭的光学和近红外再增亮不能用标准的前向激波余辉模型来解释。没有一个同期的X射线再增亮和一个强大的光谱演化的证据,在光学近红外波段的上升建议两个独立的组件,占主导地位的早期和晚期的光变曲线,分别。即使在文献中提出的替代方案的框架内,也无法解释光学上升的陡峭性,除非假设中央引擎的后期活动。

英文摘要:

Context. After the launch of the Swift satellite, the Gamma-Ray Burst (GRB) optical light-curve smoothness paradigm has been questioned thanks to the faster and better sampled optical follow-up, which has unveiled a very complex behaviour. This complexity is triggering the interest of the whole GRB community. The GROND multi-channel imager is used to study optical and near-infrared (NIR) afterglows of GRBs with unprecedented optical and near-infrared temporal and spectral resolution. The GRB 081029 has a very prominent optical rebrightening event and is an outstanding example of the application of the multi-channel imager to GRB afterglows. Aims. Here we exploit the rich GROND multi-colour follow-up of GRB 081029 combined with XRT observations to study the nature of late-time rebrightenings that appear in the optical-NIR light-curves of some GRB afterglows. Methods. We analyse the optical and NIR observations obtained with the seven-channel Gamma-Ray burst Optical and Near-infrared Detector (GROND) at the 2.2 m MPI/ESO telescope and the X-ray data obtained with the XRT telescope on board the Swift observatory. The multi-wavelength temporal and spectral evolution is discussed in the framework of different physical models. Results. The extremely steep optical and NIR rebrightening observed in GRB 081029 cannot be explained in the framework of the standard forward shock afterglow model. The absence of a contemporaneous X-ray rebrightening and the evidence of a strong spectral evolution in the optical-NIR bands during the rise suggest two separate components that dominate in the early and late-time lightcurves, respectively. The steepness of the optical rise cannot be explained even in the framework of the alternative scenarios proposed in the literature unless a late-time activity of the central engine is assumed.

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