Open AccessAfterglow light curves, viewing angle and the jet structure of γ ‐ray bursts
Author(s) -
Rossi Elena,
Lazzati Davide,
Rees Martin J.
Publication year - 2002
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2002.05363.x
Subject(s) - afterglow , physics , jet (fluid) , astrophysics , viewing angle , gamma ray burst , light curve , solid angle , lorentz factor , luminosity , ligand cone angle , optics , geometry , lorentz transformation , mechanics , galaxy , classical mechanics , mathematics , conical surface , liquid crystal display , detector
Gamma‐ray bursts are often modelled as jet‐like outflows directed towards the observer; the cone angle of the jet is then commonly inferred from the time at which there is a steepening in the power‐law decay of the afterglow. We consider an alternative model in which the jet has a beam pattern where the luminosity per unit solid angle (and perhaps also the initial Lorentz factor) decreases smoothly away from the axis, rather than having a well‐defined cone angle within which the flow is uniform. We show that the break in the afterglow light curve then occurs at a time that depends on the viewing angle. Instead of implying a range of intrinsically different jets – some very narrow, and others with a similar power spread over a wider cone – the data on afterglow breaks could be consistent with a standardized jet, viewed from different angles. We discuss the implication of this model for the luminosity function.