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.

星期五, 七月 22, 2011

Ghirlanda 2011 洛仑兹因子和光度、能量等的统计关系

主要内容:
大致上E,L正比于Gamma的平方,E_p正比于Gamma。
和Liang2010的E~Gamma^4不同。

精彩摘抄:


文章信息:

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· arXiv e-print (arXiv:1107.4096)
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Title:
Gamma Ray Bursts in the comoving frame
Authors:
Ghirlanda, G.Nava, L.Ghisellini, G.Celotti, A.Burlon, D.Covino, S.Melandri, A.
Publication:
eprint arXiv:1107.4096
Publication Date:
07/2011
Origin:
ARXIV
Keywords:
Astrophysics - High Energy Astrophysical Phenomena
Comment:
12 pages, 9 figures, 5 tables. Submitted to MNRAS
Bibliographic Code:
2011arXiv1107.4096G

Abstract

We estimate the bulk Lorentz factor Gamma_0 of 32 GRBs using the measured peak time of their afterglow light curves. We consider two possible scenarios for the estimate of Gamma_0: the case of a homogeneous circumburst medium or a wind density profile. The values of Gamma_0 are broadly distributed between few tens and several hundreds with average values ~125 and ~63 for the homogeneous and wind density profile, respectively. We find that the isotropic energy and luminosity correlate in a similar way with Gamma_0, i.e. Eiso Gamma_0^2 and Liso Gamma_0^2, while the peak energy Epeak Gamma_0. These correlations are less scattered in the wind density profile than in the homogeneous case. We then study the energetics, luminosities and spectral properties of our bursts in their comoving frame. The distribution of Liso' is very narrow with a dispersion of only one decade in the wind case, clustering around Liso'=5x10^48 erg/s. Peak photon energies cluster around Epeak'=5 keV. The newly found correlations involving Gamma_0 offer a general interpretation scheme for the spectral-energy correlations of GRBs. The Epeak-Eiso and Epeak-Liso correlations are due to the different Gamma_0 factors and the collimation-corrected correlation, Epeak-Egamma (obtained by correcting the isotropic quantities for the jet opening angle theta_j), can be explained if theta_j^2*Gamma_0=constant. Assuming the Epeak-Egamma correlation as valid, we find a typical value of theta_j*Gamma_0 ~ 5-12, in agreement with the predictions of magnetically accelerated jet models.

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