Structure of gamma-ray burst jets: intrinsic versus apparent properties

Journal
Date Issued
2015
Author(s)
•
•
Pescalli, A.
•
•
Nappo, F.
DOI
Description
We thank the anonymous referee for pointing out some inaccuracies in the manuscript draft. We also thank Davide Lazzati for patiently sharing his knowledge and understanding about jet break out simulations. We acknowledge Giacomo Bonnoli for his contribution in a discussion about statistics. G. Ghirlanda acknowledges PRIN - INAF 2011 for financial support.
Abstract
With this paper we introduce the concept of apparent structure of a gamma-ray burst (GRB) jet, as opposed to its intrinsic structure. The latter is customarily defined specifying the functions ∊(θ) (the energy emitted per jet unit solid angle) and Γ(θ) (the Lorentz factor of the emitting material); the apparent structure is instead defined by us as the isotropic equivalent energy Eiso(θv) as a function of the viewing angle θv. We show how to predict the apparent structure of a jet given its intrinsic structure. We find that a Gaussian intrinsic structure yields a power-law apparent structure: this opens a new viewpoint on the Gaussian (which can be understood as a proxy for a realistic narrow, well-collimated jet structure) as a possible candidate for a quasi-universal GRB jet structure. We show that such a model (a) is consistent with recent constraints on the observed luminosity function of GRBs; (b) implies fewer orphan afterglows with respect to the standard uniform model; (c) can break out the progenitor star (in the collapsar scenario) without wasting an unreasonable amount of energy; (d) is compatible with the explanation of the Amati correlation as a viewing angle effect; (e) can be very standard in energy content, and still yield a very wide range of observed isotropic equivalent energies.
Volume
450
Issue
4
Start page
3549
Uri
Url
Issn Identifier
0035-8711
Ads BibCode
2015MNRAS.450.3549S
Rights
open.access
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