SN 2020udy: an SN Iax with strict limits on interaction consistent with a helium-star companion

Kate Maguire*, Mark R. Magee, Giorgos Leloudas, Adam A. Miller, Georgios Dimitriadis, Miika Pursiainen, Mattia Bulla, Kishalay De, Avishay Gal-Yam, Daniel A. Perley, Christoffer Fremling, Viraj R. Karambelkar, Jakob Nordin, Simeon Reusch, Steve Schulze, Jesper Sollerman, Giacomo Terreran, Yi Yang, Eric C. Bellm, Steven L. GroomMansi M. Kasliwal, Shrinivas R. Kulkarni, Leander Lacroix, Frank J. Masci, Josiah N. Purdum, Yashvi Sharma, Roger Smith

*Corresponding author for this work

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Abstract

Early observations of transient explosions can provide vital clues to their progenitor origins. In this paper, we present the nearby Type Iax (02cx-like) supernova (SN), SN 2020udy, that was discovered within hours (∼7 h) of estimated first light. An extensive data set of ultra-violet, optical, and near-infrared observations was obtained, covering out to ∼150 d after explosion. SN 2020udy peaked at -17.86 ± 0.43 mag in the r band and evolved similarly to other 'luminous' SNe Iax, such as SNe 2005hk and 2012Z. Its well-sampled early light curve allows strict limits on companion interaction to be placed. Main-sequence companion stars with masses of 2 and 6 M are ruled out at all viewing angles, while a helium-star companion is allowed from a narrow range of angles (140-180° away from the companion). The spectra and light curves of SN 2020udy are in good agreement with those of the 'N5def' deflagration model of a near Chandrasekhar-mass carbon-oxygen white dwarf. However, as has been seen in previous studies of similar luminosity events, SN 2020udy evolves slower than the model. Broad-band linear polarization measurements taken at and after peak are consistent with no polarization, in agreement with the predictions of the companion-star configuration from the early light-curve measurements. The host galaxy environment is low metallicity and is consistent with a young stellar population. Overall, we find the most plausible explosion scenario to be the incomplete disruption of a CO white dwarf near the Chandrasekhar-mass limit, with a helium-star companion.

Original languageEnglish
JournalMonthly Notices of the Royal Astronomical Society
Volume525
Issue number1
Pages (from-to)1210-1228
ISSN0035-8711
DOIs
Publication statusPublished - 2023

Keywords

  • Supernovae: general
  • Supernovae: individual: SN 2020udy
  • Techniques: photometric
  • Techniques: polarimetric
  • Techniques: spectroscopic
  • White dwarfs

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