Exploring the diversity of kilonovae with 3D radiative transfer I. The polar direction

Fuente: arXiv
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Main Authors: Collins, Christine E., Shingles, Luke J., Vijayan, Vimal, Floers, Andreas, Just, Oliver, McNeill, Fiona, Xiong, Zewei, Bauswein, Andreas, Maguire, Kate, Sim, Stuart A.
Format: Preprint
Published: 2026
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author Collins, Christine E.
Shingles, Luke J.
Vijayan, Vimal
Floers, Andreas
Just, Oliver
McNeill, Fiona
Xiong, Zewei
Bauswein, Andreas
Maguire, Kate
Sim, Stuart A.
author_facet Collins, Christine E.
Shingles, Luke J.
Vijayan, Vimal
Floers, Andreas
Just, Oliver
McNeill, Fiona
Xiong, Zewei
Bauswein, Andreas
Maguire, Kate
Sim, Stuart A.
contents We present 3D kilonova radiative transfer simulations for a series of binary neutron star merger models. The masses of the neutron stars are varied as well as the total mass of the system and two different equations of state were used (SFHO and DD2), producing a range in dynamical ejecta masses and elemental abundance patterns. In this paper, we focus on the bolometric light curves and spectra in the polar direction for comparison with observations of the kilonova AT2017gfo. We calculate line-by-line opacities and include new calibrated lanthanide atomic data. All of the simulated spectra show strong features from Sr II, La III, Gd III and Ce III, which appear to correspond to features identified in AT2017gfo, although the simulated features are generally more blueshifted. The models with the lowest lanthanide fraction in the polar direction also show a Y II feature. Ce III, Ce II, Nd III and Nd II play an important role in shaping the spectral continuum. While the bolometric luminosities in the polar direction vary with the ejecta mass of each model, we find only little sensitivity of the spectral properties to the merger configuration. Our study demonstrates that dynamical ejecta alone can reproduce (although at earlier times) many spectral properties of AT2017gfo, suggesting dynamical ejecta may have a strong impact on the early spectral evolution. However, future simulations are needed to also elucidate the role of other ejecta components for shaping the kilonova spectrum.
format Preprint
id arxiv_https___arxiv_org_abs_2604_22671
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Exploring the diversity of kilonovae with 3D radiative transfer I. The polar direction
Collins, Christine E.
Shingles, Luke J.
Vijayan, Vimal
Floers, Andreas
Just, Oliver
McNeill, Fiona
Xiong, Zewei
Bauswein, Andreas
Maguire, Kate
Sim, Stuart A.
High Energy Astrophysical Phenomena
We present 3D kilonova radiative transfer simulations for a series of binary neutron star merger models. The masses of the neutron stars are varied as well as the total mass of the system and two different equations of state were used (SFHO and DD2), producing a range in dynamical ejecta masses and elemental abundance patterns. In this paper, we focus on the bolometric light curves and spectra in the polar direction for comparison with observations of the kilonova AT2017gfo. We calculate line-by-line opacities and include new calibrated lanthanide atomic data. All of the simulated spectra show strong features from Sr II, La III, Gd III and Ce III, which appear to correspond to features identified in AT2017gfo, although the simulated features are generally more blueshifted. The models with the lowest lanthanide fraction in the polar direction also show a Y II feature. Ce III, Ce II, Nd III and Nd II play an important role in shaping the spectral continuum. While the bolometric luminosities in the polar direction vary with the ejecta mass of each model, we find only little sensitivity of the spectral properties to the merger configuration. Our study demonstrates that dynamical ejecta alone can reproduce (although at earlier times) many spectral properties of AT2017gfo, suggesting dynamical ejecta may have a strong impact on the early spectral evolution. However, future simulations are needed to also elucidate the role of other ejecta components for shaping the kilonova spectrum.
title Exploring the diversity of kilonovae with 3D radiative transfer I. The polar direction
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2604.22671