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Type Ia supernova spectral features in the context of their host galaxy properties

Type Ia supernova spectral features in the context of their host galaxy properties
Type Ia supernova spectral features in the context of their host galaxy properties
We analyse spectroscopic measurements of 122 Type Ia supernovae (SNe Ia) with z < 0.09 discovered by the Palomar Transient Factory, focusing on the properties of the Si ii ?6355 and Ca ii ‘near-infrared triplet’ absorptions. We examine the velocities of the photospheric Si ii ?6355, and the velocities and strengths of the photospheric and high-velocity Ca ii, in the context of the stellar mass (Mstellar) and star formation rate (SFR) of the SN host galaxies, as well as the position of the SN within its host. We find that SNe Ia with faster Si ii ?6355 tend to explode in more massive galaxies, with the highest velocity events only occurring in galaxies with Mstellar > 3 × 109 M?. We also find some evidence that these highest velocity SNe Ia explode in the inner regions of their host galaxies, similar to the study of Wang et al., although the trend is not as significant in our data. We show that these trends are consistent with some SN Ia spectral models, if the host galaxy stellar mass is interpreted as a proxy for host galaxy metallicity. We study the strength of the high-velocity component of the Ca ii near-IR absorption, and show that SNe Ia with stronger high-velocity components relative to photospheric components are hosted by galaxies with low Mstellar, blue colour, and a high sSFR. Such SNe are therefore likely to arise from the youngest progenitor systems. This argues against a pure orientation effect being responsible for high-velocity features in SN Ia spectra and, when combined with other studies, is consistent with a scenario where high-velocity features are related to an interaction between the SN ejecta and circumstellar medium local to the SN.
0035-8711
354-368
Pan, Y.-C.
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Sullivan, M.
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Maguire, K.
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Gal-Yam, A.
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Hook, I. M.
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Howell, D. A.
cef584ef-f8d1-4064-9b3b-25b20c40c0bd
Nugent, P. E.
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Mazzali, P. A.
f534bbbd-2775-4e54-be75-482e698bbed4
Pan, Y.-C.
a94c45d4-778e-4eb4-9d45-de88c745f04a
Sullivan, M.
2f31f9fa-8e79-4b35-98e2-0cb38f503850
Maguire, K.
94dfab90-b220-454f-8d2a-4ab4ffe27c65
Gal-Yam, A.
21353e10-c914-495b-a841-b9b79b9b7954
Hook, I. M.
df20607e-0685-4faa-b7fc-973627dd44cc
Howell, D. A.
cef584ef-f8d1-4064-9b3b-25b20c40c0bd
Nugent, P. E.
4559da92-6f56-4810-9c9e-314d139ab34a
Mazzali, P. A.
f534bbbd-2775-4e54-be75-482e698bbed4

Pan, Y.-C., Sullivan, M., Maguire, K., Gal-Yam, A., Hook, I. M., Howell, D. A., Nugent, P. E. and Mazzali, P. A. (2015) Type Ia supernova spectral features in the context of their host galaxy properties. Monthly Notices of the Royal Astronomical Society, 446 (1), 354-368. (doi:10.1093/mnras/stu2121).

Record type: Article

Abstract

We analyse spectroscopic measurements of 122 Type Ia supernovae (SNe Ia) with z < 0.09 discovered by the Palomar Transient Factory, focusing on the properties of the Si ii ?6355 and Ca ii ‘near-infrared triplet’ absorptions. We examine the velocities of the photospheric Si ii ?6355, and the velocities and strengths of the photospheric and high-velocity Ca ii, in the context of the stellar mass (Mstellar) and star formation rate (SFR) of the SN host galaxies, as well as the position of the SN within its host. We find that SNe Ia with faster Si ii ?6355 tend to explode in more massive galaxies, with the highest velocity events only occurring in galaxies with Mstellar > 3 × 109 M?. We also find some evidence that these highest velocity SNe Ia explode in the inner regions of their host galaxies, similar to the study of Wang et al., although the trend is not as significant in our data. We show that these trends are consistent with some SN Ia spectral models, if the host galaxy stellar mass is interpreted as a proxy for host galaxy metallicity. We study the strength of the high-velocity component of the Ca ii near-IR absorption, and show that SNe Ia with stronger high-velocity components relative to photospheric components are hosted by galaxies with low Mstellar, blue colour, and a high sSFR. Such SNe are therefore likely to arise from the youngest progenitor systems. This argues against a pure orientation effect being responsible for high-velocity features in SN Ia spectra and, when combined with other studies, is consistent with a scenario where high-velocity features are related to an interaction between the SN ejecta and circumstellar medium local to the SN.

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Accepted/In Press date: 8 October 2014
e-pub ahead of print date: 11 November 2014
Published date: January 2015
Organisations: Astronomy Group

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Local EPrints ID: 394610
URI: https://eprints.soton.ac.uk/id/eprint/394610
ISSN: 0035-8711
PURE UUID: c79d98fa-5333-47a7-9f1a-1ef4b7e99568
ORCID for M. Sullivan: ORCID iD orcid.org/0000-0001-9053-4820

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Date deposited: 20 May 2016 15:53
Last modified: 15 Aug 2019 00:36

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Contributors

Author: Y.-C. Pan
Author: M. Sullivan ORCID iD
Author: K. Maguire
Author: A. Gal-Yam
Author: I. M. Hook
Author: D. A. Howell
Author: P. E. Nugent
Author: P. A. Mazzali

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