An investigation on the FWHM of absorption features of type Ia supernovae

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Hauptverfasser: Zhao, Xulin, Maeda, Keiichi, Wang, Xiaofeng
Format: Preprint
Veröffentlicht: 2026
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author Zhao, Xulin
Maeda, Keiichi
Wang, Xiaofeng
author_facet Zhao, Xulin
Maeda, Keiichi
Wang, Xiaofeng
contents We present an investigation of the full width at half maximum (FWHM, or γ) of absorption features of Type Ia supernova (SNe Ia). We found that, the average value of FWHM can be well predicted with the rest wavelength (λ). The velocity also plays an important role, as objects with a higher velocity tend to have a larger FWHM. Temperature may be the third factor, as we found that, at the same velocity (but different phases), a normal-velocity (NV) object tends to have a larger FWHM than high-velocity (HV) object. Also, 1991T/1999aa-like objects that are believed to have relatively high temperatures show the largest FWHMs if compared at the same velocity. Generally speaking, FWHM evolves very slowly with time and shows no correlation with Δm15, but 1991T/1999aa-like objects are characterized by relatively fast decreasing FWHM. On the other hand, we found that, objects with relatively small FWHMs shows a tighter correlation between absorption depth (A) and Δm15, possibly a sign of higher degree of homogeneity. We also found that A/γ of Si II λ5972 has a strong correlation with Δm15, and more importantly, a relatively slow time evolution, making it a useful luminosity estimator even in the absence of phase information.
format Preprint
id arxiv_https___arxiv_org_abs_2602_23740
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle An investigation on the FWHM of absorption features of type Ia supernovae
Zhao, Xulin
Maeda, Keiichi
Wang, Xiaofeng
High Energy Astrophysical Phenomena
We present an investigation of the full width at half maximum (FWHM, or γ) of absorption features of Type Ia supernova (SNe Ia). We found that, the average value of FWHM can be well predicted with the rest wavelength (λ). The velocity also plays an important role, as objects with a higher velocity tend to have a larger FWHM. Temperature may be the third factor, as we found that, at the same velocity (but different phases), a normal-velocity (NV) object tends to have a larger FWHM than high-velocity (HV) object. Also, 1991T/1999aa-like objects that are believed to have relatively high temperatures show the largest FWHMs if compared at the same velocity. Generally speaking, FWHM evolves very slowly with time and shows no correlation with Δm15, but 1991T/1999aa-like objects are characterized by relatively fast decreasing FWHM. On the other hand, we found that, objects with relatively small FWHMs shows a tighter correlation between absorption depth (A) and Δm15, possibly a sign of higher degree of homogeneity. We also found that A/γ of Si II λ5972 has a strong correlation with Δm15, and more importantly, a relatively slow time evolution, making it a useful luminosity estimator even in the absence of phase information.
title An investigation on the FWHM of absorption features of type Ia supernovae
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2602.23740