Exploring the origins of high-velocity features in SNe Ia with the spectral synthesis code TARDIS

Fuente: arXiv
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Main Authors: Harvey, Luke, Maguire, Kate, Holas, Alexander, Anderson, Joseph P., Chen, Ting-Wan, Galbany, Lluís, González-Gaitán, Santiago, Gromadzki, Mariusz, Müller-Bravo, Tomas E., Pignata, Giuliano, Seitenzahl, Ivo R.
Format: Preprint
Published: 2025
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author Harvey, Luke
Maguire, Kate
Holas, Alexander
Anderson, Joseph P.
Chen, Ting-Wan
Galbany, Lluís
González-Gaitán, Santiago
Gromadzki, Mariusz
Müller-Bravo, Tomas E.
Pignata, Giuliano
Seitenzahl, Ivo R.
author_facet Harvey, Luke
Maguire, Kate
Holas, Alexander
Anderson, Joseph P.
Chen, Ting-Wan
Galbany, Lluís
González-Gaitán, Santiago
Gromadzki, Mariusz
Müller-Bravo, Tomas E.
Pignata, Giuliano
Seitenzahl, Ivo R.
contents Appearing as secondary higher-velocity absorption components, high-velocity features (HVFs) have been observed in several absorption lines in many Type Ia supernovae (SNe Ia). The frequency and ubiquity of these components in silicon and calcium features specifically indicates that the mechanism through which they form must be common occurrence among the majority of SNe Ia. Here we present modelling of the HVF evolution in a sample of six well observed SNe Ia with the radiative-transfer code tardis. A base model is derived for each of the SNe to reproduce the photospheric velocity components, followed by a grid of simulations with Gaussian enhancements to the density profile at high velocities. We train a set of neural networks to emulate the impact of these density enhancements upon the simulated silicon line profile. These networks are subsequently used within a Markov-Chain Monte Carlo (MCMC) framework to infer the density enhancement parameters that most closely reproduce the HVF evolution. While we obtain good matches for the silicon profile, we find that a single density enhancement alone cannot simultaneously produce the observed silicon and calcium HVF evolution. Our findings indicate that neither the delayed-detonation mechanism, nor the double-detonation mechanism can produce these HVFs, suggesting that something may be missing from the models.
format Preprint
id arxiv_https___arxiv_org_abs_2512_13791
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Exploring the origins of high-velocity features in SNe Ia with the spectral synthesis code TARDIS
Harvey, Luke
Maguire, Kate
Holas, Alexander
Anderson, Joseph P.
Chen, Ting-Wan
Galbany, Lluís
González-Gaitán, Santiago
Gromadzki, Mariusz
Müller-Bravo, Tomas E.
Pignata, Giuliano
Seitenzahl, Ivo R.
High Energy Astrophysical Phenomena
Solar and Stellar Astrophysics
Appearing as secondary higher-velocity absorption components, high-velocity features (HVFs) have been observed in several absorption lines in many Type Ia supernovae (SNe Ia). The frequency and ubiquity of these components in silicon and calcium features specifically indicates that the mechanism through which they form must be common occurrence among the majority of SNe Ia. Here we present modelling of the HVF evolution in a sample of six well observed SNe Ia with the radiative-transfer code tardis. A base model is derived for each of the SNe to reproduce the photospheric velocity components, followed by a grid of simulations with Gaussian enhancements to the density profile at high velocities. We train a set of neural networks to emulate the impact of these density enhancements upon the simulated silicon line profile. These networks are subsequently used within a Markov-Chain Monte Carlo (MCMC) framework to infer the density enhancement parameters that most closely reproduce the HVF evolution. While we obtain good matches for the silicon profile, we find that a single density enhancement alone cannot simultaneously produce the observed silicon and calcium HVF evolution. Our findings indicate that neither the delayed-detonation mechanism, nor the double-detonation mechanism can produce these HVFs, suggesting that something may be missing from the models.
title Exploring the origins of high-velocity features in SNe Ia with the spectral synthesis code TARDIS
topic High Energy Astrophysical Phenomena
Solar and Stellar Astrophysics
url https://arxiv.org/abs/2512.13791