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Exploring the spectral diversity of low-redshift Type Ia supernovae using the Palomar Transient Factory

Exploring the spectral diversity of low-redshift Type Ia supernovae using the Palomar Transient Factory
Exploring the spectral diversity of low-redshift Type Ia supernovae using the Palomar Transient Factory
We present an investigation of the optical spectra of 264 low-redshift (z < 0.2) Type Ia supernovae (SNe Ia) discovered by the Palomar Transient Factory, an untargeted transient survey. We focus on velocity and pseudo-equivalent width measurements of the Si?ii 4130, 5972, and 6355?Å lines, as well those of the Ca?ii near-infrared (NIR) triplet, up to +5?days relative to the SN B-band maximum light. We find that a high-velocity component of the Ca?ii NIR triplet is needed to explain the spectrum in ?95 per cent of SNe Ia observed before ?5?days, decreasing to ?80 per cent at maximum. The average velocity of the Ca?ii high-velocity component is ?8500 km?s?1 higher than the photospheric component. We confirm previous results that SNe Ia around maximum light with a larger contribution from the high-velocity component relative to the photospheric component in their Ca?ii NIR feature have, on average, broader light curves and lower Ca?ii NIR photospheric velocities. We find that these relations are driven by both a stronger high-velocity component and a weaker contribution from the photospheric Ca?ii NIR component in broader light curve SNe Ia. We identify the presence of C?ii in very-early-time SN Ia spectra (before ?10?days), finding that >40 per cent of SNe Ia observed at these phases show signs of unburnt material in their spectra, and that C?ii features are more likely to be found in SNe Ia having narrower light curves.
0035-8711
3258-3274
Maguire, K.
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Sullivan, M.
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Pan, Y.-C.
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Gal-Yam, A.
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Hook, I.M.
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Howell, D.A.
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Nugent, P.E.
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Mazzali, P.
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Chotard, N.
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Clubb, K.I.
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Filippenko, A.V.
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Kasliwal, M.M.
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Kandrashoff, M.T.
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Poznanski, D.
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Saunders, C.M.
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Silverman, J.M.
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Walker, E.
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Xu, D.
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Maguire, K.
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Sullivan, M.
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Pan, Y.-C.
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Gal-Yam, A.
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Hook, I.M.
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Howell, D.A.
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Nugent, P.E.
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Mazzali, P.
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Chotard, N.
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Clubb, K.I.
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Filippenko, A.V.
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Kasliwal, M.M.
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Kandrashoff, M.T.
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Poznanski, D.
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Saunders, C.M.
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Silverman, J.M.
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Walker, E.
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Xu, D.
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Maguire, K., Sullivan, M., Pan, Y.-C., Gal-Yam, A., Hook, I.M., Howell, D.A., Nugent, P.E., Mazzali, P., Chotard, N., Clubb, K.I., Filippenko, A.V., Kasliwal, M.M., Kandrashoff, M.T., Poznanski, D., Saunders, C.M., Silverman, J.M., Walker, E. and Xu, D. (2014) Exploring the spectral diversity of low-redshift Type Ia supernovae using the Palomar Transient Factory. Monthly Notices of the Royal Astronomical Society, 444 (4), 3258-3274. (doi:10.1093/mnras/stu1607).

Record type: Article

Abstract

We present an investigation of the optical spectra of 264 low-redshift (z < 0.2) Type Ia supernovae (SNe Ia) discovered by the Palomar Transient Factory, an untargeted transient survey. We focus on velocity and pseudo-equivalent width measurements of the Si?ii 4130, 5972, and 6355?Å lines, as well those of the Ca?ii near-infrared (NIR) triplet, up to +5?days relative to the SN B-band maximum light. We find that a high-velocity component of the Ca?ii NIR triplet is needed to explain the spectrum in ?95 per cent of SNe Ia observed before ?5?days, decreasing to ?80 per cent at maximum. The average velocity of the Ca?ii high-velocity component is ?8500 km?s?1 higher than the photospheric component. We confirm previous results that SNe Ia around maximum light with a larger contribution from the high-velocity component relative to the photospheric component in their Ca?ii NIR feature have, on average, broader light curves and lower Ca?ii NIR photospheric velocities. We find that these relations are driven by both a stronger high-velocity component and a weaker contribution from the photospheric Ca?ii NIR component in broader light curve SNe Ia. We identify the presence of C?ii in very-early-time SN Ia spectra (before ?10?days), finding that >40 per cent of SNe Ia observed at these phases show signs of unburnt material in their spectra, and that C?ii features are more likely to be found in SNe Ia having narrower light curves.

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Accepted/In Press date: 4 August 2014
e-pub ahead of print date: 15 September 2014
Published date: 11 November 2014
Organisations: Astronomy Group

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Local EPrints ID: 394592
URI: https://eprints.soton.ac.uk/id/eprint/394592
ISSN: 0035-8711
PURE UUID: c48a01a4-44ce-44b8-a60c-caf1f460eee3
ORCID for M. Sullivan: ORCID iD orcid.org/0000-0001-9053-4820

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Date deposited: 20 May 2016 15:12
Last modified: 15 Aug 2019 00:36

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Contributors

Author: K. Maguire
Author: M. Sullivan ORCID iD
Author: Y.-C. Pan
Author: A. Gal-Yam
Author: I.M. Hook
Author: D.A. Howell
Author: P.E. Nugent
Author: P. Mazzali
Author: N. Chotard
Author: K.I. Clubb
Author: A.V. Filippenko
Author: M.M. Kasliwal
Author: M.T. Kandrashoff
Author: D. Poznanski
Author: C.M. Saunders
Author: J.M. Silverman
Author: E. Walker
Author: D. Xu

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