Maguire, K. and Sim, S. A. and Shingles, L. and Spyromilio, J and Jerkstrand, A. and Sullivan, M. and Chen, T.W. and Cartier, R. and Dimitriadis, G. and Frohmaier, C. and Galbany, L. and Gutiérrez, C. P. and Hosseinzadeh, G. and A. Howell, D. and Inserra, C. and Rudy, R and Sollerman, J. (2018) Using late-time optical and near-infrared spectra to constrain Type Ia supernova explosion properties. Monthly Notices of the Royal Astronomical Society, 477 (3). pp. 3567-3582. ISSN 0035-8711
Full text not available from this repository.Abstract
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 Chandrasekharmass 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 higher Si 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.