The Early Light Curve of a Type Ia Supernova 2021hpr in NGC 3147: Progenitor Constraints with the Companion Interaction Model

• DOI: 10.48550/arxiv.2303.05051
• Publication Date: 2023-05-01
• Authors: Gu Lim; Myungshin Im; Gregory S. H. Paek; Sung-Chul Yoon; Changsu Choi; Sophia Kim; J. Craig Wheeler; Benjamin P. Thomas; Jozsef Vinkó; Dohyeong Kim; Jinguk Seo; Wonseok Kang; Taewoo Kim; Hyun-Il Sung; Yonggi Kim; Joh-Na Yoon; Haeun Kim; Jeongmook Kim; Hana Bae; Shuhrat Ehgamberdiev; Otabek Burhonov; Davron Mirzaqulov
• Keywords: Type Ia supernovae; High Energy Astrophysical Phenomena (astro-ph.HE); FOS: Physical sciences; Astrophysics; Astrophysics - Astrophysics of Galaxies; Transient sources; QB460-466; Supernovae; Astrophysical explosive burning; Astrophysics - Solar and Stellar Astrophysics; Time domain astronomy; Astrophysics of Galaxies (astro-ph.GA); Astrophysics - High Energy Astrophysical Phenomena; White dwarf stars; Solar and Stellar Astrophysics (astro-ph.SR)

Abstract The progenitor system of Type Ia supernovae (SNe Ia) is expected to be a close binary system consisting of a carbon/oxygen white dwarf (WD) and a nondegenerate star or another WD. Here, we present results from high-cadence monitoring observations of SN 2021hpr in a spiral galaxy, NGC 3147, and constraints on the progenitor system based on its early multicolor light-curve data. First, we classify SN 2021hpr as a normal SN Ia from its long-term photometric and spectroscopic data. More interestingly, we found a significant “early excess” in the light curve over a simple power-law ∼t 2 evolution. The early light curve evolves from blue to red to blue during the first week. To explain this, we fitted the early part of the BVRI-band light curves with a two-component model consisting of ejecta–companion interaction and a simple power-law model. The early excess and its color can be explained by shock-cooling emission due to a companion star having a radius of 8.84 ± 0.58 R ⊙. We also examined Hubble Space Telescope preexplosion images, finding no detection of a progenitor candidate, consistent with the above result. However, we could not detect signs of a significant amount of stripped mass from a nondegenerate companion star (≲0.003 M ⊙ for Hα emission). The early excess light in the multiband light curve supports a nondegenerate companion in the progenitor system of SN 2021hpr. At the same time, the nondetection of emission lines opens the door for other methods to explain this event.