The optical emission of GRB 110205A is distinguished by two flares. We examine two possible scenarios for the optical afterglow emission. In the first scenario, the first optical flare is the reverse shock emission of...The optical emission of GRB 110205A is distinguished by two flares. We examine two possible scenarios for the optical afterglow emission. In the first scenario, the first optical flare is the reverse shock emission of the main outflow and the second one is powered by the prolonged activity of the central engine. However, we find that it is rather hard to reasonably interpret the late （t〉0.1 d） afterglow data unless the GRB efficiency is very high （~0.95）. In the second scenario, the first optical flare is the low energy prompt emission and the second one is the reverse shock of the initial outflow. Within this scenario we can interpret the late afterglow emission self-consistently. The reverse shock region may be weakly magnetized and the decline of the second optical flare may be dominated by the high latitude emission, for which strong polarization evolution accompanying the quick decline is possible, as suggested by Fan et al. in 2008. Time-resolved polarimetry by RINGO2-like polarimeters will directly test our prediction.展开更多
The afterglow of GRB 081029 showed unusual behavior, with a signifi- cant rebrightening being observed at the optical wavelength at about 3000 s after the burst. One possible explanation is that the rebrightening resu...The afterglow of GRB 081029 showed unusual behavior, with a signifi- cant rebrightening being observed at the optical wavelength at about 3000 s after the burst. One possible explanation is that the rebrightening resulted from an energy in- jection. Here we present a detailed numerical study of the energy injection process and interpret the X-ray and optical afterglow light curves of GRB 081029. In our model, we have assumed two periods of energy injection, each with a constant injec- tion power. One injection starts at 2.8 × 10^3 s and lasts for about 2500 s, with a power of 7.0 × 10^47 erg s-1. This energy injection mainly accounts for the rapid rebrighten- ing at about 3000 s. The other injection starts at 8.0 × 10^3 s and lasts for about 5000 s. The injection power is 3.5 × 10^47 erg s-1. This energy injection can help to explain the slight rebrightening at about 10 000 s. It is shown that the observed optical after- glow, especially the marked rebrightening at about 3000 s, can be reproduced well. In the X-ray band, the predicted amplitude of the rebrightening is much shallower, which is also consistent with the observed X-ray afterglow light curve. It is argued that the two periods of energy injection can be produced by clumpy materials falling onto the central compact object of the burster, which leads to an enhancement of accretion and gives rise to a strong temporary outflow.展开更多
GRB 080310的X射线耀发可能起源于中心引擎的再活动,那么,产生X射线耀发的喷流剩余动能必然在后期注入到外激波.本文研究这些注入的能量对外激波动力学及其辐射的影响.研究发现,在这样的图像下,GRB 080310早期光学余辉的观测数据能够得...GRB 080310的X射线耀发可能起源于中心引擎的再活动,那么,产生X射线耀发的喷流剩余动能必然在后期注入到外激波.本文研究这些注入的能量对外激波动力学及其辐射的影响.研究发现,在这样的图像下,GRB 080310早期光学余辉的观测数据能够得到很好的解释.同时,产生瞬时辐射的喷流与产生X射线耀发的喷流的辐射效率分别为17.7%和15.6%,这暗示这两种喷流可能具有相同的耗散机制.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.11073057)
文摘The optical emission of GRB 110205A is distinguished by two flares. We examine two possible scenarios for the optical afterglow emission. In the first scenario, the first optical flare is the reverse shock emission of the main outflow and the second one is powered by the prolonged activity of the central engine. However, we find that it is rather hard to reasonably interpret the late （t〉0.1 d） afterglow data unless the GRB efficiency is very high （~0.95）. In the second scenario, the first optical flare is the low energy prompt emission and the second one is the reverse shock of the initial outflow. Within this scenario we can interpret the late afterglow emission self-consistently. The reverse shock region may be weakly magnetized and the decline of the second optical flare may be dominated by the high latitude emission, for which strong polarization evolution accompanying the quick decline is possible, as suggested by Fan et al. in 2008. Time-resolved polarimetry by RINGO2-like polarimeters will directly test our prediction.
基金supported by the National Natural Science Foundation of China(Grant Nos. 11033002 and J1210039)the National Basic Research Program of China (973 Program, Grant No. 2009CB824800)
文摘The afterglow of GRB 081029 showed unusual behavior, with a signifi- cant rebrightening being observed at the optical wavelength at about 3000 s after the burst. One possible explanation is that the rebrightening resulted from an energy in- jection. Here we present a detailed numerical study of the energy injection process and interpret the X-ray and optical afterglow light curves of GRB 081029. In our model, we have assumed two periods of energy injection, each with a constant injec- tion power. One injection starts at 2.8 × 10^3 s and lasts for about 2500 s, with a power of 7.0 × 10^47 erg s-1. This energy injection mainly accounts for the rapid rebrighten- ing at about 3000 s. The other injection starts at 8.0 × 10^3 s and lasts for about 5000 s. The injection power is 3.5 × 10^47 erg s-1. This energy injection can help to explain the slight rebrightening at about 10 000 s. It is shown that the observed optical after- glow, especially the marked rebrightening at about 3000 s, can be reproduced well. In the X-ray band, the predicted amplitude of the rebrightening is much shallower, which is also consistent with the observed X-ray afterglow light curve. It is argued that the two periods of energy injection can be produced by clumpy materials falling onto the central compact object of the burster, which leads to an enhancement of accretion and gives rise to a strong temporary outflow.
