期刊
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
卷 447, 期 1, 页码 772-785出版社
OXFORD UNIV PRESS
DOI: 10.1093/mnras/stu2435
关键词
circumstellar matter; supernovae: general; supernovae: individual: SN2005ip; supernovae: individual: SN 2009dc; supernovae: individual: SN 2012ca; supernovae: individual: SN 2013dn
资金
- NSF [PHYS-1066293, AST-1211916]
- W. M. Keck Foundation
- NASA [NNX09AH71G, NNX09AT02G, NNX10AI27G, NNX12AE66G]
- CONACyT [INFR-2009-01-122785]
- UNAM PAPIIT [IN113810]
- UC MEXUS-CONACyT
- NSF Astronomy and Astrophysics Postdoctoral Fellowship [AST-1302771]
- TABASGO Foundation
- Richard and Rhoda Goldman Fund
- Christopher R. Redlich Fund
- NASA [132817, 117866, NNX12AE66G, NNX09AT02G, NNX09AH71G, 75071, 107390, NNX10AI27G] Funding Source: Federal RePORTER
- Division Of Astronomical Sciences
- Direct For Mathematical & Physical Scien [1302771] Funding Source: National Science Foundation
A growing subset of Type Ia supernovae (SNe Ia) shows evidence via narrow emission lines for unexpected interaction with a dense circumstellar medium (SNe IIn/Ia-CSM). The precise nature of the progenitor, however, remains debated owing to spectral ambiguities arising from a strong contribution from the CSM interaction. Late-time spectra offer potential insight if the post-shock cold, dense shell becomes sufficiently thin and/or the ejecta begin to cross the reverse shock. To date, only a few high-quality spectra of this kind exist. Here we report on the late-time optical and infrared spectra of the SNe Ia-CSM 2012ca and 2013dn. These SNe Ia-CSM spectra exhibit low [Fe III]/[Fe II] ratios and strong [Ca II] at late epochs. Such characteristics are reminiscent of the super-Chandrasekhar-mass candidate SN 2009dc, for which these features suggested a low-ionization state due to high densities, although the broad Fe features admittedly show similarities to the blue 'quasi-continuum' observed in some core collapse SNe Ibn and IIn. Neither SN 2012ca nor any of the other SNe Ia-CSM in this paper show evidence for broad oxygen, carbon, or magnesium in their spectra. Similar to the interacting Type IIn SN 2005ip, a number of high-ionization lines are identified in SN 2012ca, including [S III], [Ar III], [Ar X], [Fe VIII], [Fe X], and possibly [Fe XI]. The total bolometric energy output does not exceed 10(51) erg, but does require a large kinetic-to-radiative conversion efficiency. All of these observations taken together suggest that SNe Ia-CSM are more consistent with a thermonuclear explosion than a core collapse event, although detailed radiative transfer models are certainly necessary to confirm these results.
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