GRB 221009A afterglow from a shallow angular structured jet

Ramandeep Gill, Jonathan Granot

פרסום מחקרי: פרסום בכתב עתמאמרביקורת עמיתים


Exceptionally bright gamma-ray burst (GRB) afterglows can reveal the angular structure of their jets. GRB jets appear to have a narrow core (of half-opening angle θc), beyond which their kinetic energy drops as a power-law with angle θ from the jet's symmetry axis,. The power-law index a reflects the amount of mixing between the shocked jet and confining medium, which depends on the jet's initial magnetization. Weakly magnetized jets undergo significant mixing, leading to shallow (a ≲ 2) angular profiles. We use the exquisite multiwaveband afterglow observations of GRB 221009A to constrain the jet angular structure using a dynamical model that accounts for both the forward and reverse shocks, for a power-law external density profile, next α R-k. Both the forward shock emission, that dominates the optical and X-ray flux, and the reverse shock emission, that produces the radio afterglow, require a jet with a narrow core (θc ≈ 0.021) and a shallow angular structure (a ≈ 0.8) expanding into a stellar wind (k ≈ 2). Moreover, these data appear to favour a small fraction (ζe ≈ 10-2) of shock heated electrons forming a power-law energy distribution in both shocks.

שפה מקוריתאנגלית
עמודים (מ-עד)L78-L83
כתב עתMonthly Notices of the Royal Astronomical Society: Letters
מספר גיליון1
מזהי עצם דיגיטלי (DOIs)
סטטוס פרסוםפורסם - 1 ספט׳ 2023

הערה ביבליוגרפית

Publisher Copyright:
© 2023 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.

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