2012 Beloborodov, Andrei M. GRB的峰值频率

主要内容:
这篇文章应该很重要，说了热辐射的三种形态：Plank，Wien和Compton化。说后者就演变为了Band谱。 （我想知道Compton话后的热谱是什么样子的，就是热谱是热电子和热的种子光子产生的，这种可能在光学薄的时候出现。）

精彩摘抄:


文章信息:

· Find Similar Abstracts (with default settings below)

· arXiv e-print (arXiv:1207.2707)

· References in the Article

·

· Translate This Page

Title:		Regulation of the spectral peak in gamma-ray bursts
Authors:		Beloborodov, Andrei M.
Publication:		eprint arXiv:1207.2707
Publication Date:		07/2012
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		10 pages, submitted to ApJ
Bibliographic Code:		2012arXiv1207.2707B

Abstract

Observations of gamma-ray bursts (GRBs) indicate that the peak of the burst spectrum forms in an opaque region of an ultra-relativistic jet. Recent radiative transfer calculations support this picture and show that the spectral peak is inherited from an initially thermal photon distribution that has been modified by heating into a non-blackbody spectrum with a high-energy tail. We discuss processes that regulate the position of the spectral peak E_p and compare the expected range of E_p with observations. The opaque region of a GRB jet has three radial zones: (1) Planck zone r<R_P where a blackbody spectrum is enforced; this zone ends where Thomson optical depth decreases to 10^5. (2) Wien zone R_P<r<R_W with Kompaneets parameter y>>1 where radiation has a Wien spectrum, and (3) Comptonization zone r>R_W where radiation spectrum is broadened into a Band shape. Besides the initial jet temperature, an important factor regulating E_p is internal dissipation (of bulk motions and magnetic energy) at large distances from the central engine. Dissipation in the Planck zone reduces E_p, and dissipation in the Wien zone increases E_p. In jets with weak magnetic fields, the predicted E_p approaches but does not exceed the thermal photon energy near the central engine; it is expected to vary around 1 MeV up to a maximum value of about 10 MeV. If the jet carries an energetically important magnetic field, E_p can be increased by dissipation of magnetic energy in the Wien zone. Existing data shows a cutoff in the distribution of E_p at about 20 MeV. This suggests that Poynting flux dissipation indeed contributes to heating in the Wien zone, at least in the brightest bursts with the highest E_p.

---

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