A JWST Near- and Mid-Infrared Nebular Spectrum of the Type Ia Supernova 2021aefx
Creators: name: Kwok, Lindsey A.
name: Jha, Saurabh W.
name: Temim, Tea
name: Fox, Ori D.
name: Larison, Conor
name: Camacho-Neves, Yssavo
name: Newman, Max J. Brenner
name: Pierel, Justin D. R.
name: Foley, Ryan J.
name: Andrews, Jennifer E.
name: Badenes, Carles
name: Barna, Barnabas
name: Bostroem, K. Azalee
name: Deckers, Maxime
name: Flors, Andreas
name: Garnavich, Peter
name: Graham, Melissa L.
name: Graur, Or
name: Hosseinzadeh, Griffin
name: Howell, D. Andrew
name: Hughes, John P.
name: Johansson, Joel
name: Kendrew, Sarah
name: Kerzendorf, Wolfgang E.
name: Maeda, Keiichi
name: Maguire, Kate
name: McCully, Curtis
name: O'Brien, John T.
name: Rest, Armin
name: Sand, David J.
name: Shahbandeh, Melissa
name: Strolger, Louis-Gregory
name: Szalai, Tamas
name: Ashall, Chris
name: Baron, E.
name: Burns, Chris R.
name: DerKacy, James M.
name: Evans, Tyco Mera
name: Fisher, Alec
name: Galbany, Lluis
name: Hoeflich, Peter
name: Hsiao, Eric
name: de Jaeger, Thomas
name: Karamehmetoglu, Emir
name: Krisciunas, Kevin
name: Kumar, Sahana
name: Lu, Jing
name: Maund, Justyn
name: Mazzali, Paolo A.
name: Medler, Kyle
name: Morrell, Nidia
name: Phillips, Mark. M.
name: Shappee, Benjamin J.
name: Stritzinger, Maximilian
name: Suntzeff, Nicholas
name: Telesco, Charles
name: Tucker, Michael
name: Wang, Lifan
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: We present JWST near- and mid-infrared spectroscopic observations of the nearby normal Type Ia supernova SN 2021aefx in the nebular phase at $+255$ days past maximum light. Our Near Infrared Spectrograph (NIRSpec) and Mid Infrared Instrument (MIRI) observations, combined with ground-based optical data from the South African Large Telescope (SALT), constitute the first complete optical $+$ NIR $+$ MIR nebular SN Ia spectrum covering 0.3$-$14 $μ$m. This spectrum unveils the previously unobserved 2.5$-$5 $μ$m region, revealing strong nebular iron and stable nickel emission, indicative of high-density burning that can constrain the progenitor mass. The data show a significant improvement in sensitivity and resolution compared to previous Spitzer MIR data. We identify numerous NIR and MIR nebular emission lines from iron-group elements and as well as lines from the intermediate-mass element argon. The argon lines extend to higher velocities than the iron-group elements, suggesting stratified ejecta that are a hallmark of delayed-detonation or double-detonation SN Ia models. We present fits to simple geometric line profiles to features beyond 1.2 $μ$m and find that most lines are consistent with Gaussian or spherical emission distributions, while the [Ar III] 8.99 $μ$m line has a distinctively flat-topped profile indicating a thick spherical shell of emission. Using our line profile fits, we investigate the emissivity structure of SN 2021aefx and measure kinematic properties. Continued observations of SN 2021aefx and other SNe Ia with JWST will be transformative to the study of SN Ia composition, ionization structure, density, and temperature, and will provide important constraints on SN Ia progenitor and explosion models.
description: published in ApJ Letters, 17 pages, 12 figures