The Role of Electric Dominance for Particle Injection in Relativistic Reconnection
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866915087827075072 |
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| author | Gupta, Sanya Sridhar, Navin Sironi, Lorenzo |
| author_facet | Gupta, Sanya Sridhar, Navin Sironi, Lorenzo |
| contents | Magnetic reconnection in relativistic plasmas -- where the magnetization $σ\gg1$ -- is regarded as an efficient particle accelerator, capable of explaining the most dramatic astrophysical flares. We employ two-dimensional (2D) particle-in-cell simulations of relativistic pair-plasma reconnection with vanishing guide field and outflow boundaries to quantify the impact of the energy gain occurring in regions of electric dominance ($E>B$) for the early stages of particle acceleration (i.e., the ``injection'' stage). We calculate the mean fractional contribution $ζ(ε^\ast,ε_{\rm T}$) by $E>B$ fields to particle energization up to the injection threshold energy, $ε^\ast=σ/4$; here, $ε_{\rm T}$ is the particle energy at time $T$. We find that $ζ$ monotonically increases with $σ$ and $ε_{\rm T}$; for $σ\gtrsim 50$ and $ε_{\rm T}/σ\gtrsim 8$, we find that $\gtrsim 80\%$ of the energy gain obtained before reaching $ε^\ast=σ/4$ occurs in $E>B$ regions. We find that $ζ$ is independent of simulation box size $L_x$, as long as $ε_{\rm T}$ is normalized to the maximum particle energy, which scales as $ε_{\rm max}\propto L_{\rm x}^{1/2}$ in 2D. The distribution of energy gains $ε_χ$ acquired in $E>B$ regions can be modeled as $dN/dε_χ\proptoε_χ^{-0.35}\exp[-(ε_χ/0.06\,σ)^{0.5}]$. Our results help assess the role of electric dominance in relativistic reconnection with vanishing guide fields, which may be realized in the magnetospheres of black holes and neutron stars. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2501_00979 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | The Role of Electric Dominance for Particle Injection in Relativistic Reconnection Gupta, Sanya Sridhar, Navin Sironi, Lorenzo High Energy Astrophysical Phenomena High Energy Physics - Phenomenology Magnetic reconnection in relativistic plasmas -- where the magnetization $σ\gg1$ -- is regarded as an efficient particle accelerator, capable of explaining the most dramatic astrophysical flares. We employ two-dimensional (2D) particle-in-cell simulations of relativistic pair-plasma reconnection with vanishing guide field and outflow boundaries to quantify the impact of the energy gain occurring in regions of electric dominance ($E>B$) for the early stages of particle acceleration (i.e., the ``injection'' stage). We calculate the mean fractional contribution $ζ(ε^\ast,ε_{\rm T}$) by $E>B$ fields to particle energization up to the injection threshold energy, $ε^\ast=σ/4$; here, $ε_{\rm T}$ is the particle energy at time $T$. We find that $ζ$ monotonically increases with $σ$ and $ε_{\rm T}$; for $σ\gtrsim 50$ and $ε_{\rm T}/σ\gtrsim 8$, we find that $\gtrsim 80\%$ of the energy gain obtained before reaching $ε^\ast=σ/4$ occurs in $E>B$ regions. We find that $ζ$ is independent of simulation box size $L_x$, as long as $ε_{\rm T}$ is normalized to the maximum particle energy, which scales as $ε_{\rm max}\propto L_{\rm x}^{1/2}$ in 2D. The distribution of energy gains $ε_χ$ acquired in $E>B$ regions can be modeled as $dN/dε_χ\proptoε_χ^{-0.35}\exp[-(ε_χ/0.06\,σ)^{0.5}]$. Our results help assess the role of electric dominance in relativistic reconnection with vanishing guide fields, which may be realized in the magnetospheres of black holes and neutron stars. |
| title | The Role of Electric Dominance for Particle Injection in Relativistic Reconnection |
| topic | High Energy Astrophysical Phenomena High Energy Physics - Phenomenology |
| url | https://arxiv.org/abs/2501.00979 |