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  • The Search for Stable Nickel: Investigating the Origins of Type Ia Supernovae with Late-time Near-infrared Spectroscopy from the Carnegie Supernova Project-II

This content will become publicly available on March 23, 2027

Title: The Search for Stable Nickel: Investigating the Origins of Type Ia Supernovae with Late-time Near-infrared Spectroscopy from the Carnegie Supernova Project-II
Abstract Producing stable58Ni in Type Ia supernovae (SNe Ia) requires sufficiently high-density conditions that are not predicted for all origin scenarios, so examining the distribution of58Ni using the near-infrared (NIR) [NiII] 1.939μm line may observationally distinguish between possible progenitors and explosion mechanisms. We present 79 telluric-corrected NIR spectra of 22 low-redshift SNe Ia from the Carnegie Supernova Project-II, ranging from +50 to +505 days, including 31 previously unpublished spectra. We introduce the Gaussian Peak Ratio, a detection parameter that confirms the presence of the NIR [NiII] 1.939μm line in eight SNe in our sample. Nondetections occur at earlier phases (≤+100 days) when the NIR Ni line has not emerged yet or in low signal-to-noise spectra, yielding inconclusive results. Subluminous 86G-like SNe Ia show the earliest NIR Ni features around ∼+50 days, whereas normal-bright SNe Ia do not exhibit NIR Ni until ∼+150 days. NIR Ni features detected in our sample have low peak velocities (v∼ 1200 km s−1) and narrow line widths (≤3500 km s−1), indicating stable58Ni is centrally located. This implies high-density burning conditions in the innermost regions of SNe Ia and could be due to higher mass progenitors (i.e., near-Mch). NIR spectra of the nearly two dozen SNe Ia in our sample are compared to various model predictions and paired with early-time properties to identify ideal observation windows for future SNe Ia discovered by upcoming surveys with Rubin-LSST or the Roman Space Telescope.  more » « less
Award ID(s):
2306395 2206657
PAR ID:
10687635
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more » ; ; ; « less
Editor(s):
ApJ
Publisher / Repository:
Chicago Press
Date Published:
Journal Name:
The Astrophysical Journal
Volume:
1000
Issue:
2
ISSN:
0004-637X
Page Range / eLocation ID:
178
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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