A significantly off-centre 56Ni distribution for the low-luminosity type Ia supernova SN 2016brx from the 100IAS survey. (2nd June 2018)

• Record Type: Journal Article
• Authors: Dong, Subo; Katz, Boaz; Kollmeier, Juna A; Kushnir, Doron; Elias-Rosa, N; 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
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 479:Number 1(2018:Sep.)
• Page Start: L70
• Page End: L75
• Publication Date: 2018-06-02
• Subjects: supernovae: general -- (stars:) supernovae: individual: SN 2016brx; Astronomy -- Research -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnrasl/sly098
• Languages: English
• ISSNs: 1745-3933

Abstract

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 56 Ni 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 56 Ni distributions is collisions of white dwarfs with unequal and equal masses.