A Systematic Study of Magnetic Fields Impacts on Neutrino Transport in Core-Collapse Supernovae

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Main Authors: Luo, Yudong, Zha, Shuai, Kajino, Toshitaka
Format: Preprint
Published: 2025
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author Luo, Yudong
Zha, Shuai
Kajino, Toshitaka
author_facet Luo, Yudong
Zha, Shuai
Kajino, Toshitaka
contents We quantify the impact of strong magnetic fields (assuming $B=B_0\cdot r_0^3/r^3$ with $B_0\gtrsim 10^{16}$ G) on the neutrino transport in core-collapse supernovae (CCSNe). Magnetic fields quantize the momenta of electrons and positrons, resulting in an enhanced absorption cross section for low-energy neutrinos and suppressed chemical potentials for $e^\pm$. We include these changes in the M1 scheme for neutrino transport and perform 1-D CCSNe simulations with \texttt{GR1D}. The increased low-energy cross sections reduce the $\barν_e$ mean energy $\langle E_{\barν_e}\rangle$ while elevating the neutrino number luminosities $\mathcal{L_ν}$ for both $ν_e$ and $\barν_e$ due to the lower energy weighted spectra. The reduction of chemical potential enhances the $\barν_e$ emission while suppressing that of $ν_e$, thereby driving an increase in the electron fraction behind the stalled shock at $\sim30$--$100$ km. This further amplifies $\langle E_{ν_e}\rangle$ through an increased electron density. Consequently, magnetic fields amplify $L_{ν_e}$ by increasing both $\mathcal{L}_{ν_e}$ and $\langle E_{ν_e}\rangle$ whereas for $\barν_e$, the rise in $\mathcal{L}_{\barν_e}$ is offset by a decreased $\langle E_{\barν_e}\rangle$, leading to a minimal change in $L_{\barν_e}$. A systematic parameter scan of dipole field configurations suggests that, for $r_0 > 30$ km, $\langle E_{\barν_e} \rangle$ is significantly suppressed and $L_{ν_e}$ is enhanced if $B_0 \geq {2.7} \times 10^{16}$ G. These magnetic effects become negligible for $B_0$ below $\sim {7.4} \times 10^{15}$ G.
format Preprint
id arxiv_https___arxiv_org_abs_2512_10417
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A Systematic Study of Magnetic Fields Impacts on Neutrino Transport in Core-Collapse Supernovae
Luo, Yudong
Zha, Shuai
Kajino, Toshitaka
High Energy Astrophysical Phenomena
We quantify the impact of strong magnetic fields (assuming $B=B_0\cdot r_0^3/r^3$ with $B_0\gtrsim 10^{16}$ G) on the neutrino transport in core-collapse supernovae (CCSNe). Magnetic fields quantize the momenta of electrons and positrons, resulting in an enhanced absorption cross section for low-energy neutrinos and suppressed chemical potentials for $e^\pm$. We include these changes in the M1 scheme for neutrino transport and perform 1-D CCSNe simulations with \texttt{GR1D}. The increased low-energy cross sections reduce the $\barν_e$ mean energy $\langle E_{\barν_e}\rangle$ while elevating the neutrino number luminosities $\mathcal{L_ν}$ for both $ν_e$ and $\barν_e$ due to the lower energy weighted spectra. The reduction of chemical potential enhances the $\barν_e$ emission while suppressing that of $ν_e$, thereby driving an increase in the electron fraction behind the stalled shock at $\sim30$--$100$ km. This further amplifies $\langle E_{ν_e}\rangle$ through an increased electron density. Consequently, magnetic fields amplify $L_{ν_e}$ by increasing both $\mathcal{L}_{ν_e}$ and $\langle E_{ν_e}\rangle$ whereas for $\barν_e$, the rise in $\mathcal{L}_{\barν_e}$ is offset by a decreased $\langle E_{\barν_e}\rangle$, leading to a minimal change in $L_{\barν_e}$. A systematic parameter scan of dipole field configurations suggests that, for $r_0 > 30$ km, $\langle E_{\barν_e} \rangle$ is significantly suppressed and $L_{ν_e}$ is enhanced if $B_0 \geq {2.7} \times 10^{16}$ G. These magnetic effects become negligible for $B_0$ below $\sim {7.4} \times 10^{15}$ G.
title A Systematic Study of Magnetic Fields Impacts on Neutrino Transport in Core-Collapse Supernovae
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2512.10417