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arXiv 1802.09460astro-ph.HE
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关于Ia型超新星2007 on和2011 iv:在亮度-宽度关系的暗端的克拉塞卡质量爆炸的证据

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

摘要:

利用丰度分层技术建立了两颗过渡型Ia超新星(SNe Ia)的辐射传输模型。这两个天体--SN 2007 on和SN 2011 iv--都在同一个星系NGC 1404中爆炸,这使得可以进行直接比较。SN 2007 on合成了0.25 $M_{\odot}$的$^{56}$ Ni,其发光度低于SN 2011 iv,后者产生了0.31 $M_{\odot}$的$^{56}$ Ni。与SN 2011 iv相比,SN 2007 on的中心密度($ρ_{c}$)较低,爆炸能量($E_{\rm kin}$ $\sim 1.3\pm$ 0.3 $\times10^{51}$ erg)较高,产生的核统计平衡(NSE)元素较少(0.06 $M_{\odot}$)。SN 2011 iv的$ρ_{c}$较大,在最低速度区电子捕获率增加,产生0.35 $M_{\odot}$的稳定NSE元素。SN 2011 iv的爆炸能量为$E_{\rm kin}$ $\sim 0.9 \pm$ 0.2 $\times10^{51}$ erg。这两个物体的喷出物质量与克拉塞卡质量(CH质量)一致,它们的观测特性可以通过延迟爆炸模型的预测得到很好的描述。在这个框架内,与次亮SN 1986 G的比较表明SN 2011 iv和SN 1986 G具有不同的跃迁密度($ρ_{tr}$),但相似的$ρ_{c}$。而SN 1986 G和SN 2007 on具有相似的$ρ_{tr}$但不同的$ρ_{c}$。最后,我们研究了颜色拉伸参数$s_{BV}$与$L_{max}$的关系,并确定大部分的超新星Ia(包括亚发光的)是一致的CH-质量延迟爆轰爆炸,其中的主要参数驱动的多样性是$ρ_{tr}$。我们还发现,$ρ_{c}$是驱动二级散射观察到的亮度-宽度关系的暗淡端。

英文摘要:

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 $M_{\odot}$ of $^{56}$Ni and was less luminous than SN 2011iv, which produced 0.31 $M_{\odot}$ of $^{56}$Ni. SN 2007on had a lower central density ($ρ_{c}$) and higher explosion energy ($E_{\rm kin}$ $\sim 1.3\pm$0.3$\times10^{51}$erg) than SN 2011iv, and it produced less nuclear statistical equilibrium (NSE) elements (0.06 $M_{\odot}$). Whereas, SN 2011iv had a larger $ρ_{c}$, which increased the electron capture rate in the lowest velocity regions, and produced 0.35 $M_{\odot}$ of stable NSE elements. SN 2011iv had an explosion energy of $E_{\rm kin}$ $\sim 0.9 \pm$0.2$\times10^{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_{tr}$) but similar $ρ_{c}$. Whereas, SN 1986G and SN 2007on had a similar $ρ_{tr}$ but different $ρ_{c}$. Finally, we examine the colour-stretch parameter $s_{BV}$ vs. $L_{max}$ 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 $ρ_{tr}$. We also find $ρ_{c}$ to be driving the second order scatter observed at the faint end of the luminosity-width relationship.

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