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arXiv · 2408.01161

Magnetization Factors of Gamma-Ray Burst Jets Revealed by a Systematic Analysis of the Fermi Sample

An Li·He Gao·Lin Lan·Bing Zhang
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Abstract

The composition of gamma-ray burst (GRB) jets remained a mystery until recently. In practice, we usually characterize the magnetization of the GRB jets ($\sigma_0$) through the ratio between the Poynting flux and matter (baryonic) flux. With the increasing value of $\sigma_0$, magnetic energy gradually takes on a dominant role in the acceleration and energy dissipation of the jet, causing the proportion of thermal component in the prompt-emission spectrum of GRBs to gradually decrease or even be completely suppressed. In this work, we conducted an extensive analysis of the time-resolved spectrum for all \textit{Fermi} GRBs with known redshift, and we diagnose $\sigma_0$ for each time bin by contrasting the thermal and nonthermal radiation components. Our results suggest that most GRB jets should contain a significant magnetic energy component, likely with magnetization factors $\sigma_{0}\geq 10$. The value of $\sigma_{0}$ seems vary significantly within the same GRB. Future studies with more samples, especially those with lower-energy spectral information coverage, will further verify our results.

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An Li, He Gao, Lin Lan, Bing Zhang. 2024-08-02. Magnetization Factors of Gamma-Ray Burst Jets Revealed by a Systematic Analysis of the Fermi Sample. https://arxiv.org/abs/2408.01161

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