Panaitescu 2013 LAT光变中光子光子碰撞的光深影响

主要内容:
首先高能光子可能会和低能光子碰撞，其实产生的正负电子对会对光深有贡献。

精彩摘抄:


文章信息:

· Find Similar Abstracts (with default settings below)

· arXiv e-print (arXiv:1308.3197)

· References in the Article

· Also-Read Articles (Reads History)

·

· Translate This Page

Title:		The effect of photon-photon absorption on Fermi-LAT light-curves of GRB afterglows
Authors:		Panaitescu, A.; Vestrand, W. T.; Wozniak, P.
Publication:		eprint arXiv:1308.3197
Publication Date:		08/2013
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		8 pages, submitted to MNRAS 13 May 2013
Bibliographic Code:		2013arXiv1308.3197P

Abstract

We investigate the effect that the absorption of high-energy (above 100 MeV) photons produced in GRB afterglow shocks has on the light-curves and spectra of Fermi-LAT afterglows. Afterglows produced by the interaction of a relativistic outflow with a wind-like medium peak when the blast-wave deceleration sets in, and the afterglow spectrum could be hardening before that peak, as the optical thickness to pair-formation is decreasing. In contrast, in afterglows produced in the interaction with a homogeneous medium, the optical thickness to pair-formation should increase and yield a light-curve peak when it reaches unity, followed by a fast light-curve decay, accompanied by a spectral softening. If energy is injected in the blast-wave, then the accelerated increase of the optical thickness yields a convex afterglow light-curve. Other features, such as a double-peak light-curve or a broad hump, can arise from the evolution of the optical thickness to photon-photon absorption. Fast decays and convex light-curves are seen in a few LAT afterglows, but the expected spectral softening is rarely seen in (and difficult to measure with) LAT observations. Furthermore, for the effects of photon-photon attenuation to shape the high-energy afterglow light-curve without attenuating it too much, the ejecta initial Lorentz factor must be in a relatively narrow range (50--200), which reduces the chance of observing those effects.

---

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