Rapidly-Declining Hostless Type Ia Supernova KSP-OT-201509b from the KMTNet Supernova Program: Transitional Nature and Constraint on $^{56}$Ni Distribution and Progenitor Type
| Autor: | Yuan Qi Ni, Dong-Jin Kim, Santiago González-Gaitán, Sang Chul Kim, Maria R. Drout, Yongseok Lee, Niloufar Afsariardchi, Dae-Sik Moon, John Antoniadis, Youngdae Lee, Hong Soo Park |
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| Rok vydání: | 2021 |
| Předmět: |
Physics
High Energy Astrophysical Phenomena (astro-ph.HE) 010308 nuclear & particles physics FOS: Physical sciences Astronomy and Astrophysics Astrophysics Type (model theory) Light curve 01 natural sciences Redshift Galaxy Luminosity Stars Supernova Space and Planetary Science 0103 physical sciences Ejecta Astrophysics - High Energy Astrophysical Phenomena 010303 astronomy & astrophysics |
| DOI: | 10.48550/arxiv.2103.16663 |
| Popis: | We report the early discovery and multi-color ($BVI$) high-cadence light curve analyses of a rapidly-declining sub-Chandrasekhar Type Ia supernova KSP-OT-201509b (= AT2015cx) from the KMTNet Supernova Program. The Phillips parameter and color stretch parameter of KSP-OT-201509b (= AT2015cx) are $\Delta$$M_{B,15}$ $\simeq$ 1.62 mag and $s_{BV}$ $\simeq$ 0.54, respectively, at an inferred redshift of 0.072. These, together with other measured parameters (such as the strength of the secondary $I$-band peak, colors and luminosity), identify the source to be a rapidly-declining Type Ia of transitional nature that is closer to Branch Normal than 91bg-like. Its early light curve evolution and bolometric luminosity are consistent with those of homologously expanding ejecta powered by radioactive decay and a Type Ia SN explosion with 0.32 $\pm$ 0.01 $M_{\odot}$ of synthesized $^{56}$Ni mass, 0.84 $\pm$ 0.12 $M_{\odot}$ of ejecta mass and (0.61 $\pm$ 0.14) $\times$ 10$^{51}$ erg of ejecta kinetic energy. While its $B-V$ and $V-I$ colors evolve largely synchronously with the changes in the $I$-band light curve as found in other supernovae, we also find the presence of an early redward evolution in $V-I$ prior to --10 days since peak. The bolometric light curve of the source is compatible with a stratified $^{56}$Ni distribution extended to shallow layers of the exploding progenitor. Comparisons between the observed light curves and those predicted from ejecta-companion interactions clearly disfavor Roche Lobe-filling companion stars at large separation distances, thus supporting a double-degenerate scenario for its origin. The lack of any apparent host galaxy in our deep stack images reaching a sensitivity limit of $\sim$ 28 $\rm mag\;arcsec^{-2}$ makes KSP-OT-201509b a hostless Type Ia supernova and offers new insights into supernova host galaxy environments. Comment: 39 pages, 20 figures, To appear in ApJ |
| Databáze: | OpenAIRE |
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