Growing evidence that SNe Iax are not a one-parameter family: the case of PS1-12bwh

M. R. Magee, R. Kotak, S. A. Sim, D. Wright, S. J. Smartt, E. Berger, R. Chornock, R. J. Foley, D. A. Howell, N. Kaiser, E. A. Magnier, R. Wainscot, C. Waters

Research output: Contribution to journalArticlepeer-review

21 Downloads (Pure)


In this study, we present observations of a type Iax supernova, PS1-12bwh, discovered during the Pan-STARRS1 3π-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 (≳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.
Original languageEnglish
Article numberA62
Number of pages12
JournalAstronomy and Astrophysics
Publication statusPublished - 3 May 2017


  • supernovae: general
  • supernovae: individual: PS1-12bwh
  • UKRI
  • STFC
  • ST/L000709/1


Dive into the research topics of 'Growing evidence that SNe Iax are not a one-parameter family: the case of PS1-12bwh'. Together they form a unique fingerprint.

Cite this