Spectral classification of galaxies: An Orthogonal approach
Spectral classification of galaxies: An Orthogonal approach
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DOI：
10.1086/117587
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发表时间：
1994-11
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影响因子：
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通讯作者：
A. Connolly;A. Szalay;M. Bershady;A. Kinney;D. Calzetti
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文献类型：
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作者：
A. Connolly;A. Szalay;M. Bershady;A. Kinney;D. Calzetti
用正交基函数对星系光谱能量分布进行分类，为估计构成特定星系类型的重要光谱分量的数量提供了一种客观手段。我们应用Karhuen-Lo{e}ve变换从10个星系光谱能量分布的样本中得到光谱本征系。这些光谱覆盖了从1200aa到1mU的波长范围和从椭圆形到星暴的星系形态。我们发现，光谱类型的分布可以用前两个特征向量(或本征谱)来完全描述。导出的本征基受到原始光谱能量分布归一化的影响。我们研究了不同的归一化和加权方案，包括加权到相同的测辐射热星等和根据观察到的形态类型的分布来加权。将光谱能量分布投影到它们的本征谱上，我们发现这些系数定义了一个简单的光谱分类方案。然后，星系光谱类型可以用一个参数系列(前两个特征向量在平面上的角度)来描述。我们发现我们的光谱分类与从已发表的形态分类中确定的那些光谱分类之间的平均值具有很强的相关性。
Classification of galaxy spectral energy distributions in terms of orthogonal basis functions provides an objective means of estimating the number of significant spectral components that comprise a particular galaxy type. We apply the Karhunen-Lo\`{e}ve transform to derive a spectral eigensystem from a sample of ten galaxy spectral energy distributions. These spectra cover a wavelength range of 1200 \AA\ to 1 $\mu$m and galaxy morphologies from elliptical to starburst. We find that the distribution of spectral types can be fully described by the first two eigenvectors (or eigenspectra). The derived eigenbasis is affected by the normalization of the original spectral energy distributions. We investigate different normalization and weighting schemes, including weighting to the same bolometric magnitude and weighting by the observed distribution of morphological types. Projecting the spectral energy distributions on to their eigenspectra we find that the coefficients define a simple spectral classification scheme. The galaxy spectral types can then be described in terms of a one parameter family (the angle in the plane of the first two eigenvectors). We find a strong correlation in the mean between our spectral classifications and those determined from published morphological classifications.