Jets from Scratch: A 3D Dynamo Origin of Long Gamma-Ray Burst Jets

Fuente: arXiv
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Main Authors: Chan, Ho-Sang, Gottlieb, Ore, Jacquemin-Ide, Jonatan, Cantiello, Matteo, Renzo, Mathieu
Format: Preprint
Published: 2026
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author Chan, Ho-Sang
Gottlieb, Ore
Jacquemin-Ide, Jonatan
Cantiello, Matteo
Renzo, Mathieu
author_facet Chan, Ho-Sang
Gottlieb, Ore
Jacquemin-Ide, Jonatan
Cantiello, Matteo
Renzo, Mathieu
contents The origin of the large-scale poloidal magnetic field required to power relativistic jets in collapsars remains uncertain. While such a field may be inherited during PNS collapse, the efficiency of this process is unclear, motivating an in situ mechanism to generate poloidal fields out of the predominantly toroidal fields produced by stellar differential rotation. We present the first 3D general-relativistic magnetohydrodynamic collapsar simulations initialized with toroidal magnetic field profiles that closely follows those of pre-collapse stellar models. As the toroidal field in the disk becomes dynamically important, it seeds the dynamo, producing coherent poloidal magnetic loops that appear at $\sim \mathcal{O}(100)$ gravitational radii and are then advected inward along paths that may deviate from the disk midplane. The resulting poloidal fields thread the black hole (BH) and launch highly variable, wobbling relativistic jets on timescales of order seconds, with the onset depending on the initial magnetic field and the plasma circularization radius. Although the jets are highly variable and misaligned with the BH spin axis, they sustain $\gtrsim 10^{50}$ erg s$^{-1}$, comparable to that inferred for long gamma-ray bursts (LGRB). We identify magnetic-flux inversions driven by the stochastic dynamo, leading to the formation of striped jets that could be imprinted in LGRB light curves. These results demonstrate that the accretion0disk dynamo provides a robust pathway for jet production in collapsars across a broad range of progenitors.
format Preprint
id arxiv_https___arxiv_org_abs_2605_12931
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Jets from Scratch: A 3D Dynamo Origin of Long Gamma-Ray Burst Jets
Chan, Ho-Sang
Gottlieb, Ore
Jacquemin-Ide, Jonatan
Cantiello, Matteo
Renzo, Mathieu
High Energy Astrophysical Phenomena
General Relativity and Quantum Cosmology
The origin of the large-scale poloidal magnetic field required to power relativistic jets in collapsars remains uncertain. While such a field may be inherited during PNS collapse, the efficiency of this process is unclear, motivating an in situ mechanism to generate poloidal fields out of the predominantly toroidal fields produced by stellar differential rotation. We present the first 3D general-relativistic magnetohydrodynamic collapsar simulations initialized with toroidal magnetic field profiles that closely follows those of pre-collapse stellar models. As the toroidal field in the disk becomes dynamically important, it seeds the dynamo, producing coherent poloidal magnetic loops that appear at $\sim \mathcal{O}(100)$ gravitational radii and are then advected inward along paths that may deviate from the disk midplane. The resulting poloidal fields thread the black hole (BH) and launch highly variable, wobbling relativistic jets on timescales of order seconds, with the onset depending on the initial magnetic field and the plasma circularization radius. Although the jets are highly variable and misaligned with the BH spin axis, they sustain $\gtrsim 10^{50}$ erg s$^{-1}$, comparable to that inferred for long gamma-ray bursts (LGRB). We identify magnetic-flux inversions driven by the stochastic dynamo, leading to the formation of striped jets that could be imprinted in LGRB light curves. These results demonstrate that the accretion0disk dynamo provides a robust pathway for jet production in collapsars across a broad range of progenitors.
title Jets from Scratch: A 3D Dynamo Origin of Long Gamma-Ray Burst Jets
topic High Energy Astrophysical Phenomena
General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2605.12931