학술논문
Fast and Not-so-Furious: Case Study of the Fast and Faint Type IIb SN 2021bxu
Document Type
Working Paper
Author
Desai, Dhvanil D.; Ashall, Chris; Shappee, Benjamin J.; Morrell, Nidia; Galbany, Lluís; Burns, Christopher R.; DerKacy, James M.; Hinkle, Jason T.; Hsiao, Eric; Kumar, Sahana; Lu, Jing; Phillips, Mark M.; Shahbandeh, Melissa; Stritzinger, Maximilian D.; Baron, Eddie; Bersten, Melina C.; Brown, Peter J.; de Jaeger, Thomas; Elias-Rosa, Nancy; Folatelli, Gastón; Huber, Mark E.; Mazzali, Paolo; Müller-Bravo, Tomás E.; Piro, Anthony L.; Polin, Abigail; Suntzeff, Nicholas B.; Anderson, Joseph P.; Chambers, Kenneth C.; Chen, Ting-Wan; de Boer, Thomas; Fulton, Michael D.; Gao, Hua; Gromadzki, Mariusz; Inserra, Cosimo; Magnier, Eugene A.; Nicholl, Matt; Ragosta, Fabio; Wainscoat, Richard; Young, David R.
Source
Monthly Notices of the Royal Astronomical Society, Volume 524, Issue 1, September 2023, Pages 767-785
Subject
Language
Abstract
We present photometric and spectroscopic observations and analysis of SN 2021bxu (ATLAS21dov), a low-luminosity, fast-evolving Type IIb supernova (SN). SN 2021bxu is unique, showing a large initial decline in brightness followed by a short plateau phase. With $M_r = -15.93 \pm 0.16\, \mathrm{mag}$ during the plateau, it is at the lower end of the luminosity distribution of stripped-envelope supernovae (SE-SNe) and shows a distinct $\sim$10 day plateau not caused by H- or He-recombination. SN 2021bxu shows line velocities which are at least $\sim1500\,\mathrm{km\,s^{-1}}$ slower than typical SE-SNe. It is photometrically and spectroscopically similar to Type IIb SNe during the photospheric phases of evolution, with similarities to Ca-rich IIb SNe. We find that the bolometric light curve is best described by a composite model of shock interaction between the ejecta and an envelope of extended material, combined with a typical SN IIb powered by the radioactive decay of $^{56}$Ni. The best-fit parameters for SN 2021bxu include a $^{56}$Ni mass of $M_{\mathrm{Ni}} = 0.029^{+0.004}_{-0.005}\,\mathrm{M_{\odot}}$, an ejecta mass of $M_{\mathrm{ej}} = 0.61^{+0.06}_{-0.05}\,\mathrm{M_{\odot}}$, and an ejecta kinetic energy of $K_{\mathrm{ej}} = 8.8^{+1.1}_{-1.0} \times 10^{49}\, \mathrm{erg}$. From the fits to the properties of the extended material of Ca-rich IIb SNe we find a trend of decreasing envelope radius with increasing envelope mass. SN 2021bxu has $M_{\mathrm{Ni}}$ on the low end compared to SE-SNe and Ca-rich SNe in the literature, demonstrating that SN 2021bxu-like events are rare explosions in extreme areas of parameter space. The progenitor of SN 2021bxu is likely a low mass He star with an extended envelope.
Comment: 18 pages, 15 figures, accepted to MNRAS
Comment: 18 pages, 15 figures, accepted to MNRAS