The Spectacular Ultraviolet Flash From the Peculiar Type Ia Supernova 2019yvq

Autor: Miller, A. A., Magee, M. R., Polin, A., Maguire, K., Zimmerman, E., Yao, Y., Sollerman, J., Schulze, S., Perley, D. A., Kromer, M., Bulla, M., Andreoni, I., Bellm, E. C., De, K., Dekany, R., Delacroix, A., Dhawan, S., Fremling, C., Gal-Yam, A., Goldstein, D. A., Golkhou, V. Z., Goobar, A., Graham, M. J., Irani, I., Kasliwal, M. M., Kaye, S., Kim, Y. -L., Laher, R. R., Mahabal, A. A., Masci, F. J., Nugent, P. E., Ofek, E., Phinney, E. S., Prentice, S. J., Riddle, R., Rigault, M., Rusholme, B., Schweyer, T., Shupe, D. L., Soumagnac, M. T., Terreran, G., Walters, R., Yan, L., Zolkower, J., Kulkarni, S. R.
Rok vydání: 2020
Předmět:
Zdroj: The Astrophysical Journal, Jul 2020, Volume 898, Issue 1, id.56
Druh dokumentu: Working Paper
DOI: 10.3847/1538-4357/ab9e05
Popis: Early observations of Type Ia supernovae (SNe$\,$Ia) provide essential clues for understanding the progenitor system that gave rise to the terminal thermonuclear explosion. We present exquisite observations of SN$\,$2019yvq, the second observed SN$\,$Ia, after iPTF$\,$14atg, to display an early flash of emission in the ultraviolet (UV) and optical. Our analysis finds that SN$\,$2019yvq was unusual, even when ignoring the initial flash, in that it was moderately underluminous for an SN$\,$Ia ($M_g \approx -18.5\,$mag at peak) yet featured very high absorption velocities ($v \approx 15,000\,\mathrm{km\,s}^{-1}$ for Si II $\lambda$6355 at peak). We find that many of the observational features of SN$\,$2019yvq, aside from the flash, can be explained if the explosive yield of radioactive $^{56}\mathrm{Ni}$ is relatively low (we measure $M_{^{56}\mathrm{Ni}} = 0.31 \pm 0.05\,M_\odot$) and it and other iron-group elements are concentrated in the innermost layers of the ejecta. To explain both the UV/optical flash and peak properties of SN$\,$2019yvq we consider four different models: interaction between the SN ejecta and a nondegenerate companion, extended clumps of $^{56}\mathrm{Ni}$ in the outer ejecta, a double-detonation explosion, and the violent merger of two white dwarfs. Each of these models has shortcomings when compared to the observations; it is clear additional tuning is required to better match SN$\,$2019yvq. In closing, we predict that the nebular spectra of SN$\,$2019yvq will feature either H or He emission, if the ejecta collided with a companion, strong [Ca II] emission, if it was a double detonation, or narrow [O I] emission, if it was due to a violent merger.
Comment: 27 pages, 14 figures, accepted in ApJ
Databáze: arXiv
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