On the type Ia supernovae 2007on and 2011iv: Evidence for Chandrasekhar-mass explosions at the faint end of the luminosity-width relationship

C. Ashall; P. A. Mazzali; M. D. Stritzinger; P. Hoeflich; C. R. Burns; C. Gall; E. Y. Hsiao; M. M. Phillips; N. Morrell; R. J. Foley

doi:10.1093/mnras/sty632

paper

On the type Ia supernovae 2007on and 2011iv: Evidence for Chandrasekhar-mass explosions at the faint end of the luminosity-width relationship

arXiv:1802.09460 · doi:10.1093/mnras/sty632

Abstract

Radiative transfer models of two transitional type Ia supernova (SNe Ia) have been produced using the abundance stratification technique. These two objects --designated SN 2007on and SN 2011iv-- both exploded in the same galaxy, NGC 1404, which allows for a direct comparison. SN 2007on synthesised 0.25 $M_{⊙}$ of $^{56}$ Ni and was less luminous than SN 2011iv, which produced 0.31 $M_{⊙}$ of $^{56}$ Ni. SN 2007on had a lower central density ( $ρ_{c}$ ) and higher explosion energy ( $E_{kin}$ $\sim 1.3 \pm$ 0.3 $\times 1 0^{51}$ erg) than SN 2011iv, and it produced less nuclear statistical equilibrium (NSE) elements (0.06 $M_{⊙}$ ). Whereas, SN 2011iv had a larger $ρ_{c}$ , which increased the electron capture rate in the lowest velocity regions, and produced 0.35 $M_{⊙}$ of stable NSE elements. SN 2011iv had an explosion energy of $E_{kin}$ $\sim 0.9 \pm$ 0.2 $\times 1 0^{51}$ erg. Both objects had an ejecta mass consistent with the Chandrasekhar mass (Ch-mass), and their observational properties are well described by predictions from delayed-detonation explosion models. Within this framework, comparison to the sub-luminous SN 1986G indicates SN 2011iv and SN 1986G have different transition densities ( $ρ_{t r}$ ) but similar $ρ_{c}$ . Whereas, SN 1986G and SN 2007on had a similar $ρ_{t r}$ but different $ρ_{c}$ . Finally, we examine the colour-stretch parameter $s_{B V}$ vs. $L_{ma x}$ relation and determine that the bulk of SNe Ia (including the sub-luminous ones) are consistent with Ch-mass delayed-detonation explosions, where the main parameter driving the diversity is $ρ_{t r}$ . We also find $ρ_{c}$ to be driving the second order scatter observed at the faint end of the luminosity-width relationship.

Accepted for publication in MNRAS

On the type Ia supernovae 2007on and 2011iv: Evidence for Chandrasekhar-mass explosions at the faint end of the luminosity-width relationship

Abstract

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