- evn2024@mpifr.de
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Contribution
Unveiling the nature of thermonuclear runaway supernovae with radio observations
Speakers
- Dr. Javier MOLDON
Primary authors
- Dr. Javier MOLDON (IAA-CSIC)
Co-authors
- Dr. Miguel PEREZ-TORRES (Instituto de Astrofisica de Andalucia (IAA-CSIC))
- Dr. Eric KOOL (Stockholm University)
- Dr. Seppo MATTILA (University of Turku)
- Dr. Peter LUNDQVIST (Stockholm University)
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Content
Type Ia supernovae (SNe Ia) are thermonuclear explosions of degenerate white dwarf stars destabilized by mass accretion from a companion star. Despite SNe Ia having been used to unveil the accelerated expansion of the universe, the nature of their progenitors remains poorly understood. To distinguish between a degenerate and non-degenerate progenitor companion, one can use radio observations. A non-degenerate companion star is expected to lose material through winds or binary interaction before the explosion, and the supernova ejecta colliding with this circumstellar material should produce radio synchrotron emission. However, despite extensive efforts, including some of the deepest upper limits ever obtained by our team using e-MERLIN and the EVN, no type Ia supernova has been detected at radio wavelengths. This suggests a clean environment and a companion star that is itself a degenerate white dwarf.
Here we present the results of our study of SN 2020eyj, showing the first-ever radio detection of a SN Ia. SN 2020eyj exhibits helium-rich circumstellar material, as demonstrated by its spectral features, infrared emission, and a radio counterpart detected with e-MERLIN. Based on our modeling, we conclude that the circumstellar material probably originates from a single-degenerate binary system in which a white dwarf accretes material from a helium donor star. We will briefly discuss this detection in the context of the previous radio upper limits and their implications, and describe in detail how we achieved this remarkable result. We will also discuss how a comprehensive radio follow-up of SN 2020eyj-like SNe Ia can improve the constraints on their progenitor systems.