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

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.

arXiv commentMinor Changes. Accepted by MNRAS Letter

References in corpus (41)

• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• The Man Behind the Curtain: X-rays Drive the UV through NIR Variability in the 2013 AGN Outburst in NGC 2617
• The 6dF Galaxy Survey: Final Redshift Release (DR3) and Southern Large-Scale Structures
• Observational clues to the progenitors of Type-Ia supernovae
• WISeREP - An Interactive Supernova Data Repository
• Determining the Type, Redshift, and Age of a Supernova Spectrum
• Evidence for a Spectroscopic Sequence Among SNe Ia
• Berkeley Supernova Ia Program I: Observations, Data Reduction, and Spectroscopic Sample of 582 Low-Redshift Type Ia Supernovae
• Helium-ignited violent mergers as a unified model for normal and rapidly declining Type Ia Supernovae
• Comparative Direct Analysis of Type Ia Supernova Spectra. II. Maximum Light
• Head-on collisions of white dwarfs in triple systems could explain type Ia supernova
• Sub-Chandrasekhar-mass white dwarf detonations revisited
• An asymmetric explosion as the origin of spectral evolution diversity in type Ia supernovae
• The Carnegie Supernova Project: Intrinsic Colors of Type Ia Supernovae
• Surface Detonations in Double Degenerate Binary Systems Triggered by Accretion Stream Instabilities
• Spectrophotometric time series of SN 2011fe from the Nearby Supernova Factory
• Constraining the Type Ia Supernova Progenitor: The Search for Hydrogen in Nebular Spectra
• The properties of the peculiar Type Ia SN~1991bg. Analysis and discussion of two years of observations
• The Luminosity of SN 1999by in NGC 2841 and the Nature of `Peculiar' Type Ia Supernovae
• Spectroscopy of Type Ia Supernovae by the Carnegie Supernova Project
• ESC and KAIT Observations of the Transitional Type Ia SN 2004eo
• A New Method to Calibrate the Magnitudes of Type Ia Supernovae at Maximum Light
• No Stripped Hydrogen in the Nebular Spectra of Nearby Type Ia Supernova 2011fe
• The normal Type Ia SN 2003hv out to very late phases
• Comparative Direct Analysis of Type Ia Supernova Spectra. V. Insights from A Larger Sample and Quantitative Subclassification
• Nebular velocities in type Ia Supernovae and their relationship to light curves
• Type Ia Supernovae with Bi-Modal Explosions Are Common -- Possible Smoking Gun for Direct Collisions of White-Dwarfs
• Measuring nickel masses in Type Ia supernovae using cobalt emission in nebular phase spectra
• Using late-time optical and near-infrared spectra to constrain Type Ia supernova explosion properties
• Two transitional type~Ia supernovae located in the Fornax cluster member NGC 1404: SN 2007on and SN 2011iv
• 56Ni Production in Double Degenerate White Dwarf Collisions
• Nebular-Phase Spectra of Nearby Type Ia Supernovae
• Near-Infrared Properties of Type Ia Supernovae
• The ASAS-SN Bright Supernova Catalog -- III. 2016
• The ASAS-SN Bright Supernova Catalog $-$ II. 2015
• Predicting polarization signatures for double-detonation and delayed-detonation models of Type Ia supernovae
• How do Type Ia Supernova Nebular Spectra Depend on Explosion Properties? Insights from Systematic non-LTE Modeling
• The nebular spectra of the transitional Type Ia Supernovae 2007on and 2011iv: broad, multiple components indicate aspherical explosion cores
• Light Curves and Spectra from a Thermonuclear Explosion of a White Dwarf Merger
• [CoIII] versus NaID in type Ia supernova spectra
• Collision strengths and transition probabilities for Co III forbidden lines

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