Comprehensive observations of the bright and energetic Type Iax SN 2012Z: Interpretation as a Chandrasekhar mass white dwarf explosion

Journal
Date Issued
2015
Author(s)
Stritzinger, M. D.
•
Valenti, S.
•
Hoeflich, P.
•
Baron, E.
•
Phillips, M. M.
•
Taddia, F.
•
Foley, R. J.
•
Hsiao, E. Y.
•
Jha, S. W.
•
McCully, C.
•
Pandya, V.
•
Simon, J. D.
•
•
Brown, P. J.
•
Burns, C. R.
•
Campillay, A.
•
Contreras, C.
•
Förster, F.
•
Holmbo, S.
•
Marion, G. H.
•
Morrell, N.
•
Pignata, G.
DOI
Description
We thank M. Tanaka and V. Stanishev for providing access to their published spectra of SN 2005hk. A special thanks to L. W. Hsiao for providing assistance in some of the observations presented in this study, as well as to the Las Campanas technical staff for their continued support over the years. M. D. Stritzinger, E. Hsiao, and C. Contreras gratefully acknowledge generous support provided by the Danish Agency for Science and Technology and Innovation realized through a Sapere Aude Level 2 grant. M. D. Stritzinger, F. Taddia and S. Valenti acknowledge funding provided by the Instrument Center for Danish Astrophysics (IDA). We would like to express our thanks to Peter van Hoof for creating the Atomic Line List V2.05B18 at http://www.pa.uky.edu/~peter/newpage/ . The CSP is supported by the NSF under grants AST–0306969, AST–0607438 and AST–1008343. This work was also supported by the NSF to P. Hoeflich through grants AST–22111 and AST–23432. E. Baron was supported in part by NSF grant AST-0707704. S. Benetti, is partially supported by the PRIN-INAF 2011 with the project “Transient Universe: from ESO Large to PESSTO”. G. Pignata acknowledges support provided by the Millennium Institute of Astrophysics (MAS) through grant IC120009 of the Programa Iniciativa Cientifica Milenio del Ministerio de Economia, Fomento y Turismo de Chile. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.
Abstract
We present ultraviolet through near-infrared (NIR) broadband photometry, and visual-wavelength and NIR spectroscopy of the Type Iax supernova (SN) 2012Z. The data set consists of both early- and late-time observations, including the first late phase NIR spectrum obtained for a spectroscopically classified SN Iax. Simple model calculations of its bolometric light curve suggest SN 2012Z produced ~0.3 M☉ of 56Ni, ejected about a Chandrasekhar mass of material, and had an explosion energy of ~1051 erg, making it one of the brightest (MB = -18.3 mag) and most energetic SN Iax yet observed. The late phase (+269d) NIRspectrum of SN 2012Z is found to broadly resemble similar epoch spectra of normal SNe Ia; however, like other SNe Iax, corresponding visual-wavelength spectra differ substantially from all supernova types. Constraints from the distribution of intermediate mass elements, e.g., silicon and magnesium, indicate that the outer ejecta did not experience significant mixing during or after burning, and the late phase NIR line profiles suggests most of the 56Ni is produced during high density burning. The various observational properties of SN 2012Z are found to be consistent with the theoretical expectations of a Chandrasekhar mass white dwarf progenitor that experiences a pulsational delayed detonation, which produced several tenths of a solar mass of 56Ni during the deflagration burning phase and little (or no) 56Ni during the detonation phase. Within this scenario only a moderate amount of Rayleigh-Taylor mixing occurs both during the deflagration and fallback phase of the pulsation, and the layered structure of the intermediate mass elements is a product of the subsequent denotation phase. The fact that the SNe Iax population does not follow a tight brightness-decline relation similar to SNe Ia can then be understood in the framework of variable amounts of mixing during pulsational rebound and variable amounts of 56Ni production during the early subsonic phase of expansion.

Based on observations collected at the European Organization for Astronomical Research in the Southern Hemisphere, Chile (ESO Program 088.D-0222, 184.D-1152), the Magellan 6.5 m telescopes at Las Campanas Observatory, and the Nordic Optical Telescope, operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias; also partially based on observations made with the Southern African Large Telescope (SALT), and the W. M. Keck Observatory located on the summit of Mauna Kea.Appendix A and Tables 1-5 are available in electronic form at http://www.aanda.orgFITS files of the reduced spectra are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/573/A2

Volume
573
Start page
A2
Uri
Url
Issn Identifier
0004-6361
Ads BibCode
2015A&A...573A...2S
Rights
open.access
File(s)
Loading...
Thumbnail Image
Name

aa24168-14_2012Z.pdf

Description
PDF editoriale
Size

2.12 MB

Format

Adobe PDF

Checksum (MD5)

dc56df2b8012aa7421463aad821e6913