Kawanaka 2013 超吸积中的一种新的不稳定性可能作为伽马暴的中心引擎

主要内容:


精彩摘抄:

文章信息:

· Find Similar Abstracts (with default settings below)

· Electronic Refereed Journal Article (HTML)

· Full Refereed Journal Article (PDF/Postscript)

· arXiv e-print (arXiv:1308.3235)

· References in the article

· Also-Read Articles (Reads History)

·

· Translate This Page

Title:		The Discovery of a New Instability in a Hyperaccretion Flow and its Implication for Gamma-Ray Bursts
Authors:		Kawanaka, Norita; Mineshige, Shin; Piran, Tsvi
Affiliation:		AA(Department of Astronomy, Graduate School of Science, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan norita@astron.s.u-tokyo.ac.jp), AB(Department of Astronomy, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan), AC(Racah Institute of Physics, The Hebrew University, Jerusalem 91904, Israel)
Publication:		The Astrophysical Journal Letters, Volume 777, Issue 1, article id. L15, 5 pp. (2013). (ApJL Homepage)
Publication Date:		11/2013
Origin:		IOP
Astronomy Keywords:		accretion, accretion disks, black hole physics, gamma-ray burst: general, neutrinos
DOI:		10.1088/2041-8205/777/1/L15
Bibliographic Code:		2013ApJ...777L..15K

Abstract

A hyperaccretion flow around a stellar mass black hole is thought to be the most plausible engine that powers gamma-ray bursts (GRBs). The flow efficiently cools via neutrino emission at >~ 0.003-0.01 M _☉ s^–1 (corresponding to a luminosity of ~10⁵⁰ erg s^–1), while neither neutrino nor photon emission is efficient below this rate, so the flow should be advection-dominated. We carefully solve how a transition occurs from the advection-dominated to the neutrino-dominated branches, and find that the slope of the thermal equilibrium curve is negative in the surface density-accretion rate (Σ-\dot{M}) plane, a condition for viscous instability, at radii smaller than ~12 R _g (with R _g being the gravitational radius). We also confirm that the flow is thermally stable. The consequence of this instability is the formation of a clumpy structure in the flow. This is because the larger (respectively smaller) surface density is, the smaller (respectively larger) the mass accretion rate from the region in question becomes, leading to growth of the density contrast. The timescale for clump formation is estimated to be shorter than 0.1 s. The observational implication is discussed in the context of GRBs. We suggest that this might explain the origin of the large variability observed in the prompt emission of GRBs.

---

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