Effects of magnetically driven shocks on nucleosynthesis and kilonovae from neutron star mergers

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Hauptverfasser: Feng, Yuan, Korobkin, Oleg, Most, Elias R., Smith, Ananda F., Fontes, Christopher J.
Format: Preprint
Veröffentlicht: 2026
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author Feng, Yuan
Korobkin, Oleg
Most, Elias R.
Smith, Ananda F.
Fontes, Christopher J.
author_facet Feng, Yuan
Korobkin, Oleg
Most, Elias R.
Smith, Ananda F.
Fontes, Christopher J.
contents Neutron-star mergers can launch mildly relativistic to moderately relativistic outflows whose interaction with the ejecta can reshape kilonova emission. We parametrically study magnetically powered outbursts from long-lived merger remnants, such as flare-like eruptions and collapse-driven shocks, and quantify their impact on ejecta dynamics, composition, and observables. Using two-dimensional special-relativistic magnetohydrodynamic simulations, we follow magnetized blast waves injected into expanding merger ejecta for early- and late-launch scenarios across a range of shock strengths. We then post-process Lagrangian tracer histories with the nuclear reaction network WinNet and the radiative-transfer code SuperNu with realistic opacities, to connect shock heating directly to nucleosynthesis and kilonova light curves. We find that sufficiently strong shocks can reheat portions of the ejecta to nuclear statistical equilibrium, increase the electron fraction in the shocked material, and deposit entropy, leading to systematic changes in $r$-process yields. These thermodynamic and compositional changes can leave observable imprints on kilonova emission -- especially in color evolution and late-time light-curve behavior -- indicating that magnetically driven remnant variability can potentially contribute to kilonova diversity.
format Preprint
id arxiv_https___arxiv_org_abs_2605_03947
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Effects of magnetically driven shocks on nucleosynthesis and kilonovae from neutron star mergers
Feng, Yuan
Korobkin, Oleg
Most, Elias R.
Smith, Ananda F.
Fontes, Christopher J.
High Energy Astrophysical Phenomena
Neutron-star mergers can launch mildly relativistic to moderately relativistic outflows whose interaction with the ejecta can reshape kilonova emission. We parametrically study magnetically powered outbursts from long-lived merger remnants, such as flare-like eruptions and collapse-driven shocks, and quantify their impact on ejecta dynamics, composition, and observables. Using two-dimensional special-relativistic magnetohydrodynamic simulations, we follow magnetized blast waves injected into expanding merger ejecta for early- and late-launch scenarios across a range of shock strengths. We then post-process Lagrangian tracer histories with the nuclear reaction network WinNet and the radiative-transfer code SuperNu with realistic opacities, to connect shock heating directly to nucleosynthesis and kilonova light curves. We find that sufficiently strong shocks can reheat portions of the ejecta to nuclear statistical equilibrium, increase the electron fraction in the shocked material, and deposit entropy, leading to systematic changes in $r$-process yields. These thermodynamic and compositional changes can leave observable imprints on kilonova emission -- especially in color evolution and late-time light-curve behavior -- indicating that magnetically driven remnant variability can potentially contribute to kilonova diversity.
title Effects of magnetically driven shocks on nucleosynthesis and kilonovae from neutron star mergers
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2605.03947