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Article Dans Une Revue The Astrophysical Journal Année : 2010

Nearby Supernova Factory Observations of SN 2007if: First Total Mass Measurement of a Super-Chandrasekhar-Mass Progenitor

R. A. Scalzo
  • Fonction : Auteur
G. Aldering
  • Fonction : Auteur
C. Aragon
  • Fonction : Auteur
M. Childress
  • Fonction : Auteur
N. Chotard
  • Fonction : Auteur
Y. Copin
H. K. Fakhouri
  • Fonction : Auteur
A. Gal-Yam
S. Hoyer
  • Fonction : Auteur
M. Kasliwal
  • Fonction : Auteur
S. Loken
  • Fonction : Auteur
P. E. Nugent
  • Fonction : Auteur
S. Perlmutter
  • Fonction : Auteur
D. Rabinowitz
  • Fonction : Auteur
A. Rau
  • Fonction : Auteur
K. Runge
  • Fonction : Auteur
R. C. Thomas
  • Fonction : Auteur
B. Weaver
  • Fonction : Auteur

Résumé

We present photometric and spectroscopic observations of SN 2007if, an overluminous (M_V = -20.4), red (B-V = 0.16 at B-band maximum), slow-rising (t_rise = 24 days) type Ia supernova in a very faint (M_g = -14.10) host galaxy. A spectrum at 5 days past B-band maximum light is a direct match to the super-Chandrasekhar-mass candidate SN Ia 2003fg, showing Si II and C II at ~9000 km/s. A high signal-to-noise co-addition of the SN spectral time series reveals no Na I D absorption, suggesting negligible reddening in the host galaxy, and the late-time color evolution has the same slope as the Lira relation for normal SNe Ia. The ejecta appear to be well mixed, with no strong maximum in I-band and a diversity of iron-peak lines appearing in near-maximum-light spectra. SN2007 if also displays a plateau in the Si II velocity extending as late as +10 days, which we interpret as evidence for an overdense shell in the SN ejecta. We calculate the bolometric light curve of the SN and use it and the \ion{Si}{2} velocity evolution to constrain the mass of the shell and the underlying SN ejecta, and demonstrate that SN2007 if is strongly inconsistent with a Chandrasekhar-mass scenario. Within the context of a "tamped detonation" model appropriate for double-degenerate mergers, and assuming no host extinction, we estimate the total mass of the system to be 2.4 +/- 0.2 solar masses, with 1.6 +/- 0.1 solar masses of nickel-56 and with 0.3-0.5 solar masses in the form of an envelope of unburned carbon/oxygen. Our modeling demonstrates that the kinematics of shell entrainment provide a more efficient mechanism than incomplete nuclear burning for producing the low velocities typical of super-Chandrasekhar-mass SNeIa.

Dates et versions

in2p3-00465857 , version 1 (22-03-2010)

Identifiants

Citer

R. A. Scalzo, G. Aldering, P. Antilogus, C. Aragon, S. Bailey, et al.. Nearby Supernova Factory Observations of SN 2007if: First Total Mass Measurement of a Super-Chandrasekhar-Mass Progenitor. The Astrophysical Journal, 2010, 713, pp.1073-1094. ⟨10.1088/0004-637X/713/2/1073⟩. ⟨in2p3-00465857⟩
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