A significantly off-centre 56Ni distribution for the low-luminosity type Ia supernova SN 2016brx from the 100IAS survey
- 2 June 2018
- journal article
- research article
- Published by Oxford University Press (OUP) in Monthly Notices of the Royal Astronomical Society: Letters
- Vol. 479 (1), L70-L75
- https://doi.org/10.1093/mnrasl/sly098
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.Funding Information
- China Postdoctoral Science Foundation (2016M600848)
- FONDECYT (1151445)
- University of Calgary (PR2017-64)
- Gordon and Betty Moore Foundation (GBMF5490)
- National Sleep Foundation (AST-1515927, AST-0908816)
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