伽玛暴(Gamma-Ray Burst)笔记。记录有关伽玛暴的新文章,另外也包括看的老文章、自己的想法、以及跟天文相关的一些东西。 Feel free to leave me a message by comments or by email.

星期二, 四月 08, 2008

Fujimoto 2008 喷流中的核合成

主要内容:
考虑磁场主导的喷流中的核合成,认为喷流的能量越高,产生的Ni56越多。而象060614和060605这样的低能量的暴,产生的Ni56就比较少,因为没有超新星成分。 也就是说他们还是认为这两个暴是大质量恒星坍缩引起的。

精彩摘抄:


文章信息:

· arXiv e-print (arXiv:0804.0969)
· References in the Article
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Title:
Nucleosynthesis in Magnetically Driven Jets from Collapsars
Authors:
Fujimoto, Shin-ichiro; Nishimura, Nobuya; Hashimoto, Masa-aki
Publication:
eprint arXiv:0804.0969
Publication Date:
04/2008
Origin:
ARXIV
Keywords:
Astrophysics
Comment:
10 pages, 14 figures, 1 table, Accepted for publication in the Astroph ysical Journal
Bibliographic Code:
2008arXiv0804.0969F

Abstract

We have made detailed calculations of the composition of magnetically driven jets ejected from collapsars, or rapidly rotating massive stars, based on long-term magnetohydrodynamic simulations of their core collapse with various distributions of magnetic field and angular momentum before collapse. We follow the evolution of the abundances of about 4000 nuclides from the collapse phase to the ejection phase and through the jet generation phase using a large nuclear reaction network. We find that the r-process successfully operates only in energetic jets (> 1e51 ergs), such that U and Th are synthesized abundantly, even when the collapsar has a relatively weak magnetic field (1e10 G) and a moderately rotating core before the collapse. The abundance patterns inside the jets are similar to those of the r-elements in the solar system. About 0.01-0.06 Msun neutron-rich, heavy nuclei are ejected from a collapsar with energetic jets. The higher energy jets have larger amounts of Ni56, varying from 0.00037 to 0.06Msun. Less energetic jets, which eject small amounts of Ni56, could induce a gamma-ray burst (GRB) a supernova, such as GRB 060505 or GRB 060614. Considerable amounts of r-elements are likely to be ejected from GRBs with hypernovae, if both the GRB and hypernova are induced by jets that are driven near the black hole.
Bibtex entry for this abstract Preferred format for this abstract (see Preferences)

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