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| Format: | Preprint |
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2026
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| Online Access: | https://arxiv.org/abs/2604.26194 |
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| _version_ | 1866911630654177280 |
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| author | Liang, Shi-Min Zhang, Jian-Fu Yi, Nian-Yu |
| author_facet | Liang, Shi-Min Zhang, Jian-Fu Yi, Nian-Yu |
| contents | We perform numerical simulations of particle acceleration in relativistic, self-driven turbulent magnetic reconnection using the MHD-PIC method. We systematically investigate the dependence of the non-thermal particle spectral exponent on the plasma $β$. We find that particle acceleration proceeds in two stages: an initial, efficient first-order Fermi phase where momentum gains are comparable in parallel and perpendicular directions, followed by a slower drift-dominated phase. The power-law slope of the non-thermal spectrum is established during the Fermi phase, as found in previous studies. Our results demonstrate a systematic steepening of the accelerated particle energy spectrum with increasing $β$. We derive empirical scaling relations: the spectral exponent $α\propto β^{0.5}$ in the relativistic regime, compared to $α\propto β^{0.3}$ in the non-relativistic case. This marked difference is rooted in relativistic physics: the increased inertial mass density ($ρh$) in high-$β$ plasmas acts as an energy sink, reducing the Alfvén velocity and thereby altering the dynamics of magnetic energy release and its partition efficiency. The derived scaling provides a unified physical framework for interpreting the diversity of non-thermal radiation spectra observed in astrophysical sources, including black hole corona X-ray flares, gamma-ray bursts, and active galactic nucleus jets. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2604_26194 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | The $β$-Dependence of Particle Spectra in Relativistic Turbulent Reconnection Liang, Shi-Min Zhang, Jian-Fu Yi, Nian-Yu High Energy Astrophysical Phenomena We perform numerical simulations of particle acceleration in relativistic, self-driven turbulent magnetic reconnection using the MHD-PIC method. We systematically investigate the dependence of the non-thermal particle spectral exponent on the plasma $β$. We find that particle acceleration proceeds in two stages: an initial, efficient first-order Fermi phase where momentum gains are comparable in parallel and perpendicular directions, followed by a slower drift-dominated phase. The power-law slope of the non-thermal spectrum is established during the Fermi phase, as found in previous studies. Our results demonstrate a systematic steepening of the accelerated particle energy spectrum with increasing $β$. We derive empirical scaling relations: the spectral exponent $α\propto β^{0.5}$ in the relativistic regime, compared to $α\propto β^{0.3}$ in the non-relativistic case. This marked difference is rooted in relativistic physics: the increased inertial mass density ($ρh$) in high-$β$ plasmas acts as an energy sink, reducing the Alfvén velocity and thereby altering the dynamics of magnetic energy release and its partition efficiency. The derived scaling provides a unified physical framework for interpreting the diversity of non-thermal radiation spectra observed in astrophysical sources, including black hole corona X-ray flares, gamma-ray bursts, and active galactic nucleus jets. |
| title | The $β$-Dependence of Particle Spectra in Relativistic Turbulent Reconnection |
| topic | High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2604.26194 |