Mon. Not. R. Astron. Soc., 477, 3567-3582 (2018/July-1)
Using late-time optical and near-infrared spectra to constrain Type Ia supernova explosion properties.
MAGUIRE K., SIM S.A., SHINGLES L., SPYROMILIO J., JERKSTRAND A., SULLIVAN M., CHEN T.-W., CARTIER R., DIMITRIADIS G., FROHMAIER C., GALBANY L., GUTIERREZ C.P., HOSSEINZADEH G., HOWELL D.A., INSERRA C., RUDY R. and SOLLERMAN J.
Abstract (from CDS):
The late-time spectra of Type Ia supernovae (SNe Ia) are powerful probes of the underlying physics of their explosions. We investigate the late-time optical and near-infrared spectra of seven SNe Ia obtained at the VLT with XShooter at >200 d after explosion. At these epochs, the inner Fe-rich ejecta can be studied. We use a line-fitting analysis to determine the relative line fluxes, velocity shifts, and line widths of prominent features contributing to the spectra ([Fe II], [Ni II], and [Co III]). By focusing on [Fe II] and [Ni II] emission lines in the ∼7000-7500 Å region of the spectrum, we find that the ratio of stable [Ni II] to mainly radioactively produced [Fe II] for most SNe Ia in the sample is consistent with Chandrasekhar-mass delayed-detonation explosion models, as well as sub-Chandrasekhar mass explosions that have metallicity values above solar. The mean measured Ni/Fe abundance of our sample is consistent with the solar value. The more highly ionized [Co III] emission lines are found to be more centrally located in the ejecta and have broader lines than the [Fe II] and [Ni II] features. Our analysis also strengthens previous results that SNe Ia with higherSi II velocities at maximum light preferentially display blueshifted [Fe II] 7155 Å lines at late times. Our combined results lead us to speculate that the majority of normal SN Ia explosions produce ejecta distributions that deviate significantly from spherical symmetry.
© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society
line: profiles - techniques: spectroscopic - supernovae: general
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