早期SN 2011 fe观测的谱模型
Spectral Models for Early Time SN 2011fe Observations
摘要：
我们使用观察到的紫外线通过近红外光谱，以检查是否SN 2011 fe可以理解的框架内的分支正常SNe Ia和检查其个别的特点。作为基准，我们使用延迟爆轰模型与祖金属丰度Z_太阳能/20。我们研究的灵敏度特征的变化，在祖金属丰度，外密度分布，放射性镍的分布。母体中金属丰度变化的影响对合成光谱的影响相对较小。我们还发现，SN 2011 fe的丰度分层非常类似于延迟爆轰模型的过渡密度，已适合其他分支正常的Ia型超新星。在早期，模型光球是在速度太高的物质中形成的，这表明光球退得太慢，或者SN 2011 fe在~0.1 M太阳外的比能比模型低。我们讨论几种解释的差异。最后，我们研究的光谱能量分布和颜色的变化，由于在祖金属丰度的变化，这表明，颜色只是弱指标的祖金属丰度，在特定的爆炸模型，我们已经研究。我们发现，在U波段的通量是显着较高的太阳能金属丰度模型在最大光比在较低的金属丰度模型和较低的金属丰度模型更好地匹配观测到的光谱。
英文摘要：
We use observed UV through near IR spectra to examine whether SN 2011fe can be understood in the framework of Branch-normal SNe Ia and to examine its individual peculiarities. As a benchmark, we use a delayed-detonation model with a progenitor metallicity of Z_solar/20. We study the sensitivity of features to variations in progenitor metallicity, the outer density profile, and the distribution of radioactive nickel. The effect of metallicity variations in the progenitor have a relatively small effect on the synthetic spectra. We also find that the abundance stratification of SN 2011fe resembles closely that of a delayed detonation model with a transition density that has been fit to other Branch-normal Type Ia supernovae. At early times, the model photosphere is formed in material with velocities that are too high, indicating that the photosphere recedes too slowly or that SN 2011fe has a lower specific energy in the outer ~0.1 M_sun than does the model. We discuss several explanations for the discrepancies. Finally, we examine variations in both the spectral energy distribution and in the colors due to variations in the progenitor metallicity, which suggests that colors are only weak indicators for the progenitor metallicity, in the particular explosion model that we have studied. We do find that the flux in the U band is significantly higher at maximum light in the solar metallicity model than in the lower metallicity model and the lower metallicity model much better matches the observed spectrum.
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