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arXiv 1107.4631astro-ph.CO
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Ia型超新星距离模内禀散射的更一般模型

A More General Model for the Intrinsic Scatter in Type Ia Supernova Distance Moduli

John Marriner, J. P. Bernstein, Richard Kessler, Hubert Lampeitl, Ramon Miquel, Jennifer Mosher, Robert C. Nichol, Masao Sako, Donald P. Schneider, Mathew Smith

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摘要：

我们描述了一种新的形式主义，以适应的参数$α$和$β$中使用的SALT 2模型，以确定标准的Ia型超新星的星等。新的形式主义描述的内在散射在Ia型超新星的协方差矩阵，而不是通常使用的单一参数。我们已经应用这种形式主义的斯隆数字巡天超新星巡天（SDSS-II）的数据，并得出结论，数据是最好的描述由$α=0.135_{-.017}^{+.033}$和$β=3.19_{-0.24}^{+0.14}$，其中的错误是由不确定性的形式的内在散射矩阵。我们的结果取决于一个更一般的形式的Ia型超新星的距离模量的内在散射比传统的介绍，从而在一个更大的值$β$和一个更大的不确定性比传统的方法。虽然这种分析导致$β$的值更大，误差更大，但SDSS数据与$β=4.1$不同（在98%的置信水平上），$β=4.1$是银河系中发现的尘埃类型预期的灭绝值。我们已经模拟了超新星Ia的分布在他们的颜色，并得出结论，有强有力的证据表明，颜色的变化是一个显着的贡献者超新星Ia的分散在他们的标准烛光等。

英文摘要：

We describe a new formalism to fit the parameters $α$ and $β$ that are used in the SALT2 model to determine the standard magnitudes of Type Ia supernovae. The new formalism describes the intrinsic scatter in Type Ia supernovae by a covariance matrix in place of the single parameter normally used. We have applied this formalism to the Sloan Digital Sky Survey Supernova Survey (SDSS-II) data and conclude that the data are best described by $α=0.135_{-.017}^{+.033}$ and $β=3.19_{-0.24}^{+0.14}$, where the error is dominated by the uncertainty in the form of the intrinsic scatter matrix. Our result depends on the introduction of a more general form for the intrinsic scatter of the distance moduli of Type Ia supernovae than is conventional, resulting in a larger value of $β$ and a larger uncertainty than the conventional approach. Although this analysis results in a larger value of $β$ and a larger error, the SDSS data differ (at a 98% confidence level) with $β=4.1$, the value expected for extinction by the type of dust found in the Milky Way. We have modeled the distribution of supernovae Ia in terms of their color and conclude that there is strong evidence that variation in color is a significant contributor to the scatter of supernovae Ia around their standard candle magnitude.

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