A significantly off-centre 56Ni distribution for the low-luminosity type Ia supernova SN 2016brx from the 100IAS survey
Date Issued
2018
Author(s)
Dong, Subo
•
Katz, Boaz
•
Kollmeier, Juna A.
•
Kushnir, Doron
•
•
Bose, Subhash
•
Morrell, Nidia
•
Prieto, J. L.
•
Chen, Ping
•
Kochanek, C. S.
•
Brandt, G. M.
•
Holoien, T. W. -S.
•
Gal-Yam, Avishay
•
Morales-Garoffolo, Antonia
•
Parker, Stuart
•
Phillips, M. M.
•
Piro, Anthony L.
•
Shappee, B. J.
•
Simon, Joshua D.
•
Stanek, K. Z.
Abstract
We present nebular-phase spectra of the Type Ia supernova (SN Ia) 2016brx, a member of the 1991bg-like subclass that lies at the faint end of the SN Ia luminosity function. Nebular spectra are available for only three other 1991bg-like SNe, and their Co line centres are all within ≲500 km s-1 of each other. In contrast, the nebular Co line centre of SN 2016brx is blue-shifted by >1500 km s-1 compared to them and by ≈1200 km s-1 compared to the rest frame. This is a significant shift relative to the narrow nebular line velocity dispersion of ≲2000 km s-1 of these SNe. The large range of nebular line shifts implies that the 56Ni in the ejecta of SN 1991bg-like events is off-centre by ∼1000 km s-1 rather than universally centrally confined as previously suggested. With the addition of SN 2016brx, the Co nebular line shapes of 1991bg-like objects appear to connect with the brighter SNe Ia that show double-peaked profiles, hinting at a continuous distribution of line profiles among SNe Ia. One class of models to produce both off-centre and bimodal 56Ni distributions is collisions of white dwarfs with unequal and equal masses.
Volume
479
Issue
1
Start page
L70
Issn Identifier
0035-8711
Ads BibCode
2018MNRAS.479L..70D
Rights
open.access
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