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

A. A. Miller, M. R. Magee, A. Polin, K. Maguire, E. Zimmerman, Y. Yao, J. Sollerman, S. Schulze, D. A. Perley, M. Kromer, M. Bulla, I. Andreoni, E. C. Bellm, K. De, R. Dekany, A. Delacroix, S. Dhawan, C. Fremling, A. Gal-Yam, D. A. Goldstein, V. Z. Golkhou, A. Goobar, M. J. Graham, I. Irani, M. M. Kasliwal, S. Kaye, Y. -L. Kim, R. R. Laher, A. A. Mahabal, F. J. Masci, P. E. Nugent, E. Ofek, E. S. Phinney, S. J. Prentice, R. Riddle, M. Rigault, B. Rusholme, T. Schweyer, D. L. Shupe, M. T. Soumagnac, G. Terreran, R. Walters, L. Yan, J. Zolkower, S. R. Kulkarni

July 2020

Abstract

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 ($Mg approx -18.5, $m a g a t p e a k) y e t f e a t u r e d v e r y h i g h a b s o r p t i o n v e l o c i t i e s ($ v approx 15,000,mathrm{km,s}^{-1} $f o r S i I I$ lambda $6355 a t p e a k) . W e f i n d t h a t m a n y o f t h e o b s e r v a t i o n a l f e a t u r e s o f S N$ , $2019 y v q, a s i d e f r o m t h e f l a s h, c a n b e e x p l a i n e d i f t h e e x p l o s i v e y i e l d o f r a d i o a c t i v e$ ^{56}mathrm{Ni} $i s r e l a t i v e l y l o w (w e m e a s u r e$ M{^{56}mathrm{Ni}} = 0.31 pm 0.05,M_odot $) a n d i t a n d o t h e r i r o n - g r o u p e l e m e n t s a r e c o n c e n t r a t e d i n t h e i n n e r m o s t l a y e r s o f t h e e j e c t a . T o e x p l a i n b o t h t h e U V / o p t i c a l f l a s h a n d p e a k p r o p e r t i e s o f S N$ , $2019 y v q w e c o n s i d e r f o u r d i f f e r e n t m o d e l s : i n t e r a c t i o n b e t w e e n t h e S N e j e c t a a n d a n o n d e g e n e r a t e c o m p a n i o n, e x t e n d e d c l u m p s o f$ ^{56}mathrm{Ni} $i n t h e o u t e r e j e c t a, a d o u b l e - d e t o n a t i o n e x p l o s i o n, a n d t h e v i o l e n t m e r g e r o f t w o w h i t e d w a r f s . E a c h o f t h e s e m o d e l s h a s s h o r t c o m i n g s w h e n c o m p a r e d t o t h e o b s e r v a t i o n s; i t i s c l e a r a d d i t i o n a l t u n i n g i s r e q u i r e d t o b e t t e r m a t c h S N$ , $2019 y v q . I n c l o s i n g, w e p r e d i c t t h a t t h e n e b u l a r s p e c t r a o f S N$ ,$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.

Type

Journal article

http://arxiv.org/abs/2005.05972v2