Flight of the Bumblebee : the Early Excess Flux of Type Ia Supernova 2023bee Revealed by TESS, Swift, and Young Supernova Experiment Observations

Wang, Qinan and Rest, Armin and Dimitriadis, Georgios and Ridden-Harper, Ryan and Siebert, Matthew R. and Magee, Mark and Angus, Charlotte R. and Auchettl, Katie and Davis, Kyle W. and Foley, Ryan J. and Fox, Ori D. and Gomez, Sebastian and Jencson, Jacob E. and Jones, David O. and Kilpatrick, Charles D. and Pierel, Justin D. R. and Piro, Anthony L. and Polin, Abigail and Politsch, Collin A. and Rojas-Bravo, César and Shahbandeh, Melissa and Villar, V. Ashley and Zenati, Yossef and Ashall, C. and Chambers, Kenneth C. and Coulter, David A. and de Boer, Thomas and DiLullo, Nico and Gall, Christa and Gao, Hua and Hsiao, Eric Y. and Huber, Mark E. and Izzo, Luca and Khetan, Nandita and LeBaron, Natalie and Magnier, Eugene A. and Mandel, Kaisey S. and McGill, Peter and Miao, Hao-Yu and Pan, Yen-Chen and Stevens, Catherine P. and Swift, Jonathan J. and Taggart, Kirsty and Yang, Grace (2024) Flight of the Bumblebee : the Early Excess Flux of Type Ia Supernova 2023bee Revealed by TESS, Swift, and Young Supernova Experiment Observations. The Astrophysical Journal, 962 (1): 17. ISSN 0004-637X

Abstract

We present high-cadence ultraviolet through near-infrared observations of the Type Ia supernova (SN Ia) 2023bee at D = 32 ± 3 Mpc, finding excess flux in the first days after explosion, particularly in our 10 minutes cadence TESS light curve and Swift UV data. Compared to a few other normal SNe Ia with early excess flux, the excess flux in SN 2023bee is redder in the UV and less luminous. We present optical spectra of SN 2023bee, including two spectra during the period where the flux excess is dominant. At this time, the spectra are similar to those of other SNe Ia but with weaker Si ii, C ii, and Ca ii absorption lines, perhaps because the excess flux creates a stronger continuum. We compare the data to several theoretical models on the origin of early excess flux in SNe Ia. Interaction with either the companion star or close-in circumstellar material is expected to produce a faster evolution than observed. Radioactive material in the outer layers of the ejecta, either from double detonation explosion or from a 56Ni clump near the surface, cannot fully reproduce the evolution either, likely due to the sensitivity of early UV observable to the treatment of the outer part of ejecta in simulation. We conclude that no current model can adequately explain the full set of observations. We find that a relatively large fraction of nearby, bright SNe Ia with high-cadence observations have some amount of excess flux within a few days of explosion. Considering potential asymmetric emission, the physical cause of this excess flux may be ubiquitous in normal SNe Ia.