High-velocity features of calcium and silicon in the spectra of Type Ia supernovae

Jeffrey M. Silverman, J. Vinkó, G. H. Marion, J. Craig Wheeler, Barnabás Barna, Tamás Szalai, Brian W. Mulligan, Alexei V. Filippenko

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

'High-velocity features' (HVFs) are spectral features in Type Ia supernovae (SNe Ia) that have minima indicating significantly higher (by greater than about 6000 km s-1) velocities than typical 'photospheric-velocity features' (PVFs). The PVFs are absorption features with minima indicating typical photospheric (i.e. bulk ejecta) velocities (usually~9000-15 000 km s-1 near B-band maximum brightness). In this work, we undertake the most in-depth study of HVFs ever performed. The data set used herein consists of 445 low-resolution optical and nearinfrared (NIR) spectra (at epochs up to 5 d past maximum brightness) of 210 low-redshift SNe Ia that follow the 'Phillips relation'. A series of Gaussian functions is fit to the data in order to characterize possible HVFs of Ca II H&K, Si II λ6355, and the Ca II NIR triplet. The temporal evolution of the velocities and strengths of the PVFs and HVFs of these three spectral features is investigated, as are possible correlations with other SN Ia observables. We find that while HVFs of Ca II are regularly observed (except in underluminous SNe Ia, where they are never found), HVFs of Si II λ6355 are significantly rarer, and they tend to exist at the earliest epochs and mostly in objects with large photospheric velocities. It is also shown that stronger HVFs of Si II λ6355 are found in objects that lack C II absorption at early times and that have red ultraviolet/optical colours near maximum brightness. These results lead to a self-consistent connection between the presence and strength of HVFs of Si II λ6355 and many other mutually correlated SN Ia observables, including photospheric velocity.

Original languageEnglish
Pages (from-to)1973-2014
Number of pages42
JournalMonthly Notices of the Royal Astronomical Society
Volume451
Issue number2
DOIs
Publication statusPublished - May 1 2015

Fingerprint

silicon
supernovae
calcium
brightness
time measurement
ejecta
temporal evolution

Keywords

  • Methods: data analysis
  • Supernovae: general
  • Techniques: spectroscopic

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Silverman, J. M., Vinkó, J., Marion, G. H., Craig Wheeler, J., Barna, B., Szalai, T., ... Filippenko, A. V. (2015). High-velocity features of calcium and silicon in the spectra of Type Ia supernovae. Monthly Notices of the Royal Astronomical Society, 451(2), 1973-2014. https://doi.org/10.1093/mnras/stv1011

High-velocity features of calcium and silicon in the spectra of Type Ia supernovae. / Silverman, Jeffrey M.; Vinkó, J.; Marion, G. H.; Craig Wheeler, J.; Barna, Barnabás; Szalai, Tamás; Mulligan, Brian W.; Filippenko, Alexei V.

In: Monthly Notices of the Royal Astronomical Society, Vol. 451, No. 2, 01.05.2015, p. 1973-2014.

Research output: Contribution to journalArticle

Silverman, JM, Vinkó, J, Marion, GH, Craig Wheeler, J, Barna, B, Szalai, T, Mulligan, BW & Filippenko, AV 2015, 'High-velocity features of calcium and silicon in the spectra of Type Ia supernovae', Monthly Notices of the Royal Astronomical Society, vol. 451, no. 2, pp. 1973-2014. https://doi.org/10.1093/mnras/stv1011
Silverman, Jeffrey M. ; Vinkó, J. ; Marion, G. H. ; Craig Wheeler, J. ; Barna, Barnabás ; Szalai, Tamás ; Mulligan, Brian W. ; Filippenko, Alexei V. / High-velocity features of calcium and silicon in the spectra of Type Ia supernovae. In: Monthly Notices of the Royal Astronomical Society. 2015 ; Vol. 451, No. 2. pp. 1973-2014.
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AU - Szalai, Tamás

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