A1 Refereed original research article in a scientific journal
The aspherical explosions of the 03fg-like Type Ia supernovae 2021zny and 2022ilv revealed by polarimetry
Authors: Nagao, T.; Maeda, K.; Mattila, S.; Kuncarayakti, H.; Gutierrez, C. P.; Cikota, A.
Publisher: EDP Sciences
Publishing place: LES ULIS CEDEX A
Publication year: 2024
Journal: Astronomy and Astrophysics
Journal name in source: ASTRONOMY & ASTROPHYSICS
Journal acronym: ASTRON ASTROPHYS
Article number: L19
Volume: 687
Number of pages: 6
ISSN: 0004-6361
eISSN: 1432-0746
DOI: https://doi.org/10.1051/0004-6361/202449999
Web address : https://www.aanda.org/articles/aa/full_html/2024/07/aa49999-24/aa49999-24.html
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/457358431
Preprint address: https://arxiv.org/abs/2406.18110
Context. A peculiar subtype of Type Ia supernovae (SNe), 03fg-like (super-Chandrasekhar) SNe, show different observational properties from prototypical Type Ia SNe: they typically have high luminosities at the light-curve peak, low expansion velocities, and strong carbon features. The origin of this class of Type Ia SNe has been actively debated. Recent nebular-phase infrared observations of the 03fg-like Type Ia SN 2022pul using the James Webb Space Telescope revealed large-scale asymmetries in the ejecta and the presence of the strong [Ne II] line at 12.81 mu m, suggesting a violent merger of two white dwarfs as its origin.
Aims. Polarimetry is another powerful tool for studying the overall ejecta asymmetries of spatially unresolved SNe. Here, we aim to check the universality of the violent merger scenario as the origin of 03fg-like Type Ia SNe, by studying their explosion geometries using polarimetry.
Methods. In this Letter we present imaging-polarimetric observations of the two 03fg-like Type Ia SNe 2021zny and 2022ilv.
Results. SNe 2021zny and 2022ilv show high intrinsic polarization (similar to 1%-similar to 2%), which might be composed of multiple components with different polarization angles. This indicates that they have complex aspherical structures in their ejecta, supporting the violent merger scenario for their origin. Our observations provide the first clear evidence from polarimetry for such aspherical structures.
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Funding information in the publication:
TN acknowledges support from the Research Council of Finland projects 324504, 328898 and 353019. KM acknowledges support from the Japan Society for the Promotion of Science (JSPS) KAKENHI grant (JP20H00174 and JP24H01810) and by the JSPS Open Partnership Bilateral Joint Research Project between Japan and Finland (JPJSBP120229923). S. M. was funded by the Research Council of Finland project 350458. HK was funded by the Research Council of Finland projects 324504, 328898, and 353019. CPG acknowledges financial support from the Secretary of Universities and Research (Government of Catalonia) and by the Horizon 2020 Research and Innovation Programme of the European Union under the Marie Skłodowska-Curie and the Beatriu de Pinós 2021 BP 00168 programme, from the Spanish Ministerio de Ciencia e Innovación (MCIN) and the Agencia Estatal de Investigación (AEI) 10.13039/501100011033 under the PID2020-115253GA-I00 HOSTFLOWS project, and the program Unidad de Excelencia María de Maeztu CEX2020-001058-M.
