A1 Refereed original research article in a scientific journal
Growing evidence that SNe Iax are not a one-parameter family The case of PS1-12bwh
Authors: Magee MR, Kotak R, Sim SA, Wright D, Smartt SJ, Berger E, Chornock R, Foley RJ, Howell DA, Kaiser N, Magnier EA, Wainscoat R, Waters C
Publisher: EDP SCIENCES S A
Publication year: 2017
Journal: Astronomy and Astrophysics
Journal name in source: ASTRONOMY & ASTROPHYSICS
Journal acronym: ASTRON ASTROPHYS
Article number: ARTN A62
Volume: 601
Number of pages: 12
ISSN: 1432-0746
DOI: https://doi.org/10.1051/0004-6361/201629643
Self-archived copy’s web address: https://research.utu.fi/converis/portal/Publication/38803438
In this study, we present observations of a type Iax supernova, PS1-12bwh, discovered during the Pan-STARRS1 3 pi-survey. Our analysis was driven by previously unseen pre-maximum, spectroscopic heterogeneity. While the light curve and post-maximum spectra of PS1-12bwh are virtually identical to those of the well-studied type Iax supernova, SN 2005hk, the -2 day spectrum of PS1-12bwh does not resemble SN 2005hk at a comparable epoch; instead, we found it to match a spectrum of SN 2005hk taken over a week earlier (12 day). We are able to rule out the cause as being incorrect phasing, and argue that it is not consistent with orientation effects predicted by existing explosion simulations. To investigate the potential source of this difference, we performed radiative transfer modelling of both supernovae. We found that the pre-maximum spectrum of PS1-12bwh is well matched by a synthetic spectrum generated from a model with a lower density in the high velocity (greater than or similar to 6000 km s(-1)) ejecta than SN 2005hk. The observed differences between SN 2005hk and PS1-12bwh may therefore be attributed primarily to differences in the high velocity ejecta alone, while comparable densities for the lower velocity ejecta would explain the nearly identical post-maximum spectra. These two supernovae further highlight the diversity within the SNe Iax class, as well as the challenges in spectroscopically identifying and phasing these objects, especially at early epochs.
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