主要内容:
首先是理论, 然后是应用到早期X射线余辉的shallow decay
精彩摘抄:
文章信息:
- · Electronic On-line Article (HTML)
- · arXiv e-print (arXiv:0908.4511)
- · References in the Article
- · Also-Read Articles (Reads History)
- ·
- · Translate This Page
| Title: |
| Early afterglows from radially structured outflows and the application to X-ray shallow decays |
| Authors: |
| Liu, Xue-Wen; Wu, Xue-Feng; Zou, Yuan-Chuan; Lu, Tan |
| Publication: |
| eprint arXiv:0908.4511 |
| Publication Date: |
| 08/2009 |
| Origin: |
| ARXIV |
| Keywords: |
| Astrophysics - High Energy Astrophysical Phenomena |
| Comment: |
| Research in Astron. Astrophys., 2009, Vol. 9, No. 8, 911-920 |
| Bibliographic Code: |
| 2009arXiv0908.4511L |
Abstract
In the fireball model, it is more physically realistic that gamma-ray burst (GRB) ejecta have a range of bulk Lorentz factors (assuming $M\propto \Gamma^{-s}$). The low Lorentz factor part of the ejecta will catch up with the high Lorentz factor part when the latter is decelerated by the surrounding medium to a comparable Lorentz factor. Such a process will develop a long-lasting weak reverse shock until the whole ejecta are shocked. Meanwhile, the forward shocked materials are gradually supplied with energy from the ejecta that are catching-up, and thus the temporal decay of the forward shock emission will be slower than that without an energy supply. However, the reverse shock may be strong. Here, we extend the standard reverse-forward shock model to the case of radially nonuniform ejecta. We show that this process can be classified into two cases: the thick shell case and the thin shell case. In the thin shell case, the reverse shock is weak and the temporal scaling law of the afterglow is the same as that in Sari & Mesz (2000). However, in the thick shell case, the reverse shock is strong and thus its emission dominates the afterglow in the high energy band. Our results also show slower decaying behavior of the afterglow due to the energy supply by low Lorentz factor materials, which may help the understanding of the plateau observed in the early optical and X-ray afterglows.
没有评论:
发表评论