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arXiv · 1805.00010

A Significantly off-center Ni56 Distribution for the Low-Luminosity Type Ia Supernova SN 2016brx from the 100IAS survey

Subo Dong·Boaz Katz·Juna A. Kollmeier·Doron Kushnir·N. Elias-Rosa·Subhash Bose·Nidia Morrell·J. L. Prieto·Ping Chen·C. S. Kochanek·G. M. Brandt·T. W. -S. Holoien·Avishay Gal-Yam·Antonia Morales-Garoffolo·Stuart Parker·M. M. Phillips·Anthony L. Piro·B. J. Shappee·Joshua D. Simon·K. Z. Stanek
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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 centers are all within <~ 500 km/s of each other. In contrast, the nebular Co line center of SN 2016brx is blue-shifted by >1500 km/s compared to them and by ~1200 km/s compared to the rest frame. This is a significant shift relative to the narrow nebular line velocity dispersion of <~ 2000 km/s of these SNe. The large range of nebular line shifts implies that the Ni56 in the ejecta of SN 1991bg-like events is off-center by ~1000 km/s 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-peak profiles, hinting at a continuous distribution of line profiles among SNe Ia. One class of models to produce both off-center and bi-modal Ni56 distributions is collisions of white dwarfs with unequal and equal masses.

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Subo Dong, Boaz Katz, Juna A. Kollmeier, Doron Kushnir, N. Elias-Rosa, Subhash Bose, Nidia Morrell, J. L. Prieto, Ping Chen, C. S. Kochanek, G. M. Brandt, T. W. -S. Holoien, Avishay Gal-Yam, Antonia Morales-Garoffolo, Stuart Parker, M. M. Phillips, Anthony L. Piro, B. J. Shappee, Joshua D. Simon, K. Z. Stanek. 2018-04-30. A Significantly off-center Ni56 Distribution for the Low-Luminosity Type Ia Supernova SN 2016brx from the 100IAS survey. https://doi.org/10.1093/mnrasl%2Fsly098

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