ASASSN-15pz: Revealing Significant Photometric Diversity among 2009dc-like, Peculiar SNe Ia

Ping Chen; Subo Dong; Boaz Katz; C. S. Kochanek; Juna A. Kollmeier; K. Maguire; M. M. Phillips; J. L. Prieto; B. J. Shappee; M. D. Stritzinger; Subhash Bose; Peter J. Brown; T. W.S. Holoien; L. Galbany; Peter A. Milne; Nidia Morrell; Anthony L. Piro; K. Z. Stanek; Todd A. Thompson; D. R. Young

doi:10.3847/1538-4357/ab2630

ASASSN-15pz: Revealing Significant Photometric Diversity among 2009dc-like, Peculiar SNe Ia

Ping Chen, Subo Dong, Boaz Katz, C. S. Kochanek, Juna A. Kollmeier, K. Maguire, M. M. Phillips, J. L. Prieto, B. J. Shappee, M. D. Stritzinger, Subhash Bose, Peter J. Brown, T. W.S. Holoien, L. Galbany, Peter A. Milne, Nidia Morrell, Anthony L. Piro, K. Z. Stanek, Todd A. Thompson, D. R. Young

Steward Observatory

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Abstract

We report comprehensive multi-wavelength observations of a peculiar Type Ia-like supernova ("SN Ia-pec") ASASSN-15pz. ASASSN-15pz is a spectroscopic "twin" of SN 2009dc, a so-called "Super-Chandrasekhar-mass" SN, throughout its evolution, but it has a peak luminosity M_B,peak = -19.69 0.12 mag that is 0.6 mag dimmer and comparable to the SN 1991T sub-class of SNe Ia at the luminous end of the normal width-luminosity relation. The synthesized 56Ni mass of M₅₆Ni = 1.13 ± 0.14 M_⊙ is also substantially less than that found for several 2009dc-like SNe. Previous well-studied 2009dc-like SNe have generally suffered from large and uncertain amounts of host-galaxy extinction, which is negligible for ASASSN-15pz. Based on the color of ASASSN-15pz, we estimate a host extinction for SN 2009dc of E(B - V)host = 0.12 mag and confirm its high luminosity (M_B,peak [2009dc] -20.3 mag). The 2009dc-like SN population, which represents ∼1% of SNe Ia, exhibits a range of peak luminosities, and do not fit onto the tight width-luminosity relation. Their optical light curves also show significant diversity of late-time (≲50 days) decline rates. The nebular-phase spectra provide powerful diagnostics to identify the 2009dc-like events as a distinct class of SNe Ia. We suggest referring to these sources using the phenomenology-based "2009dc-like SN Ia-pec" instead of "Super-Chandrasekhar SN Ia," which is based on an uncertain theoretical interpretation.

Original language	English (US)
Article number	35
Journal	Astrophysical Journal
Volume	880
Issue number	1
DOIs	https://doi.org/10.3847/1538-4357/ab2630
State	Published - Jul 20 2019

Keywords

supernovae: general
supernovae: individual (ASASSN-15pz)

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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Chen, P., Dong, S., Katz, B., Kochanek, C. S., Kollmeier, J. A., Maguire, K., Phillips, M. M., Prieto, J. L., Shappee, B. J., Stritzinger, M. D., Bose, S., Brown, P. J., Holoien, T. W. S., Galbany, L., Milne, P. A., Morrell, N., Piro, A. L., Stanek, K. Z., Thompson, T. A., & Young, D. R. (2019). ASASSN-15pz: Revealing Significant Photometric Diversity among 2009dc-like, Peculiar SNe Ia. Astrophysical Journal, 880(1), Article 35. https://doi.org/10.3847/1538-4357/ab2630

Chen, P, Dong, S, Katz, B, Kochanek, CS, Kollmeier, JA, Maguire, K, Phillips, MM, Prieto, JL, Shappee, BJ, Stritzinger, MD, Bose, S, Brown, PJ, Holoien, TWS, Galbany, L, Milne, PA, Morrell, N, Piro, AL, Stanek, KZ, Thompson, TA & Young, DR 2019, 'ASASSN-15pz: Revealing Significant Photometric Diversity among 2009dc-like, Peculiar SNe Ia', Astrophysical Journal, vol. 880, no. 1, 35. https://doi.org/10.3847/1538-4357/ab2630

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title = "ASASSN-15pz: Revealing Significant Photometric Diversity among 2009dc-like, Peculiar SNe Ia",

abstract = "We report comprehensive multi-wavelength observations of a peculiar Type Ia-like supernova ({"}SN Ia-pec{"}) ASASSN-15pz. ASASSN-15pz is a spectroscopic {"}twin{"} of SN 2009dc, a so-called {"}Super-Chandrasekhar-mass{"} SN, throughout its evolution, but it has a peak luminosity MB,peak = -19.69 0.12 mag that is 0.6 mag dimmer and comparable to the SN 1991T sub-class of SNe Ia at the luminous end of the normal width-luminosity relation. The synthesized 56Ni mass of M56Ni = 1.13 ± 0.14 M⊙ is also substantially less than that found for several 2009dc-like SNe. Previous well-studied 2009dc-like SNe have generally suffered from large and uncertain amounts of host-galaxy extinction, which is negligible for ASASSN-15pz. Based on the color of ASASSN-15pz, we estimate a host extinction for SN 2009dc of E(B - V)host = 0.12 mag and confirm its high luminosity (MB,peak [2009dc] -20.3 mag). The 2009dc-like SN population, which represents ∼1% of SNe Ia, exhibits a range of peak luminosities, and do not fit onto the tight width-luminosity relation. Their optical light curves also show significant diversity of late-time (≲50 days) decline rates. The nebular-phase spectra provide powerful diagnostics to identify the 2009dc-like events as a distinct class of SNe Ia. We suggest referring to these sources using the phenomenology-based {"}2009dc-like SN Ia-pec{"} instead of {"}Super-Chandrasekhar SN Ia,{"} which is based on an uncertain theoretical interpretation.",

keywords = "supernovae: general, supernovae: individual (ASASSN-15pz)",

author = "Ping Chen and Subo Dong and Boaz Katz and Kochanek, {C. S.} and Kollmeier, {Juna A.} and K. Maguire and Phillips, {M. M.} and Prieto, {J. L.} and Shappee, {B. J.} and Stritzinger, {M. D.} and Subhash Bose and Brown, {Peter J.} and Holoien, {T. W.S.} and L. Galbany and Milne, {Peter A.} and Nidia Morrell and Piro, {Anthony L.} and Stanek, {K. Z.} and Thompson, {Todd A.} and Young, {D. R.}",

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T2 - Revealing Significant Photometric Diversity among 2009dc-like, Peculiar SNe Ia

AU - Chen, Ping

AU - Dong, Subo

AU - Katz, Boaz

AU - Kochanek, C. S.

AU - Kollmeier, Juna A.

AU - Maguire, K.

AU - Phillips, M. M.

AU - Prieto, J. L.

AU - Shappee, B. J.

AU - Stritzinger, M. D.

AU - Bose, Subhash

AU - Brown, Peter J.

AU - Holoien, T. W.S.

AU - Galbany, L.

AU - Milne, Peter A.

AU - Morrell, Nidia

AU - Piro, Anthony L.

AU - Stanek, K. Z.

AU - Thompson, Todd A.

AU - Young, D. R.

PY - 2019/7/20

Y1 - 2019/7/20

N2 - We report comprehensive multi-wavelength observations of a peculiar Type Ia-like supernova ("SN Ia-pec") ASASSN-15pz. ASASSN-15pz is a spectroscopic "twin" of SN 2009dc, a so-called "Super-Chandrasekhar-mass" SN, throughout its evolution, but it has a peak luminosity MB,peak = -19.69 0.12 mag that is 0.6 mag dimmer and comparable to the SN 1991T sub-class of SNe Ia at the luminous end of the normal width-luminosity relation. The synthesized 56Ni mass of M56Ni = 1.13 ± 0.14 M⊙ is also substantially less than that found for several 2009dc-like SNe. Previous well-studied 2009dc-like SNe have generally suffered from large and uncertain amounts of host-galaxy extinction, which is negligible for ASASSN-15pz. Based on the color of ASASSN-15pz, we estimate a host extinction for SN 2009dc of E(B - V)host = 0.12 mag and confirm its high luminosity (MB,peak [2009dc] -20.3 mag). The 2009dc-like SN population, which represents ∼1% of SNe Ia, exhibits a range of peak luminosities, and do not fit onto the tight width-luminosity relation. Their optical light curves also show significant diversity of late-time (≲50 days) decline rates. The nebular-phase spectra provide powerful diagnostics to identify the 2009dc-like events as a distinct class of SNe Ia. We suggest referring to these sources using the phenomenology-based "2009dc-like SN Ia-pec" instead of "Super-Chandrasekhar SN Ia," which is based on an uncertain theoretical interpretation.

AB - We report comprehensive multi-wavelength observations of a peculiar Type Ia-like supernova ("SN Ia-pec") ASASSN-15pz. ASASSN-15pz is a spectroscopic "twin" of SN 2009dc, a so-called "Super-Chandrasekhar-mass" SN, throughout its evolution, but it has a peak luminosity MB,peak = -19.69 0.12 mag that is 0.6 mag dimmer and comparable to the SN 1991T sub-class of SNe Ia at the luminous end of the normal width-luminosity relation. The synthesized 56Ni mass of M56Ni = 1.13 ± 0.14 M⊙ is also substantially less than that found for several 2009dc-like SNe. Previous well-studied 2009dc-like SNe have generally suffered from large and uncertain amounts of host-galaxy extinction, which is negligible for ASASSN-15pz. Based on the color of ASASSN-15pz, we estimate a host extinction for SN 2009dc of E(B - V)host = 0.12 mag and confirm its high luminosity (MB,peak [2009dc] -20.3 mag). The 2009dc-like SN population, which represents ∼1% of SNe Ia, exhibits a range of peak luminosities, and do not fit onto the tight width-luminosity relation. Their optical light curves also show significant diversity of late-time (≲50 days) decline rates. The nebular-phase spectra provide powerful diagnostics to identify the 2009dc-like events as a distinct class of SNe Ia. We suggest referring to these sources using the phenomenology-based "2009dc-like SN Ia-pec" instead of "Super-Chandrasekhar SN Ia," which is based on an uncertain theoretical interpretation.

KW - supernovae: general

KW - supernovae: individual (ASASSN-15pz)

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ASASSN-15pz: Revealing Significant Photometric Diversity among 2009dc-like, Peculiar SNe Ia

Abstract

Keywords

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