Harikae 2009 狭义相对论下的慢旋转坍缩星MHD模拟

主要内容:
存在一个critical角动量, 低于那个值, 就不能形成吸积盘, 物质都直接掉到黑洞(这时候不是也有能量释放的吗?).

不过这个模拟还是存在能量没观测要求那么多的问题.

精彩摘抄:


文章信息:

· Find Similar Abstracts (with default settings below)

· arXiv e-print (arXiv:0905.2006)

· References in the Article

·

· Translate This Page

Title:		Long-Term Evolution of Slowly Rotating Collapsar in Special Relativistic Magnetohydrodynamics
Authors:		Harikae, Seiji.; Takiwaki, Tomoya.; Kotake, Kei.
Publication:		eprint arXiv:0905.2006
Publication Date:		05/2009
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		44 pages with 17 figures
Bibliographic Code:		2009arXiv0905.2006H

Abstract

We present our numerical results of two-dimensional magnetohydrodynamic (MHD) simulations of the collapse of rotating massive stars in light of the collapsar model of gamma-ray bursts (GRBs). Pushed by recent evolution calculations of GRB progenitors, we focus on lower angular momentum of the central core than the ones taken mostly in previous studies. By performing special relativistic simulations including both realistic equation of state and neutrino coolings, we follow a unprecedentedly long-term evolution of the slowly rotating collapsars up to $\sim$ 10 s, accompanied by the formation of jets and accretion disks. Our results show that for the GRB progenitors to function as collapsars, there is a critical initial angular momentum, below which matter is quickly swallowed to the central objects, no accretion disks and no MHD outflows are formed. When larger than the criteria, we find the launch of the MHD jets in the following two ways. For models with stronger initial magnetic fields, the magnetic pressure amplified inside the accretion disk can drive the MHD outflows, which makes the strong magnetic explosions like a 'magnetic tower' (type II). For the models with weaker initial magnetic fields, the magnetic tower stalls first and the subsequent MHD outflows are produced by some eventual inflows of the accreting material from the equator to the polar regions (type I). Regardless of type I or II, the jets can attain only mildly relativistic speeds with the explosion energy less than $10^{49} \erg$, which could possibly be related to the X-ray flashes. Due to high opacity for neutrinos inside the disk, we find that the luminosities of $\nu_e$ and $\bar{\nu}_e$ become almost comparable, which is advantageous for making the energy deposition rate larger.

---

Bibtex entry for this abstract Preferred format for this abstract (see Preferences)