CHARACTERIZING ULTRAVIOLET AND INFRARED OBSERVATIONAL PROPERTIES FOR GALAXIES. II. FEATURES OF ATTENUATION LAW
CHARACTERIZING ULTRAVIOLET AND INFRARED OBSERVATIONAL PROPERTIES FOR GALAXIES. II. FEATURES OF ATTENUATION LAW
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DOI：
10.1088/0004-637x/789/1/76
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发表时间：
2014-06
期刊：
影响因子：
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通讯作者：
Y. Mao;X. Kong;Lin Lin-Lin
中科院分区：
文献类型：
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作者：
Y. Mao;X. Kong;Lin Lin-Lin
衰减定律的变化对观测到的星系光谱能量分布有重要影响。红外-紫外光度比与紫外色指数（或紫外光谱斜率）的相关性是星系在紫外和红外波段的一个重要观测性质，IRX-UV关系（或称IRX-β关系）是一个广泛应用的星系尘埃衰减修正公式，但由于许多研究发现该关系存在较大的离散性，其实用性受到质疑。在本文中，光谱合成建模和空间分辨测量的四个附近的旋涡星系的基础上，我们提供了一个解释的偏差的IRX-UV关系的变化的衰减规律。从理论和观测的角度来看，衰减曲线中的两个组成部分，线性背景和2175年的碰撞，建议作为参数，除了恒星的人口年龄（在本系列的第一篇论文中解决）的IRX-UV函数;不同的功能在衰减曲线诊断我们的样本中的星系。然而，在实际观测中，确定星系的衰减规律往往是困难的。本文还讨论了阻碍衰减曲线参数成功探测的可能原因，包括观测通道中线性背景的简并性和2175年的扰动，对年轻和富尘系统的研究要求，以及难以准确估计不同波段的尘埃衰减。
Variations in the attenuation law have a significant impact on observed spectral energy distributions for galaxies. As one important observational property for galaxies at ultraviolet and infrared wavelength bands, the correlation between infrared-to-ultraviolet luminosity ratio and ultraviolet color index (or ultraviolet spectral slope), i.e., the IRX–UV relation (or IRX–β relation), offered a widely used formula for correcting dust attenuation in galaxies, but the usability appears to be in doubt now because of considerable dispersion in this relation found by many studies. In this paper, on the basis of spectral synthesis modeling and spatially resolved measurements of four nearby spiral galaxies, we provide an interpretation of the deviation in the IRX–UV relation with variations in the attenuation law. From both theoretical and observational viewpoints, two components in the attenuation curve, the linear background and the 2175 Å bump, are suggested to be the parameters in addition to the stellar population age (addressed in the first paper of this series) in the IRX–UV function; different features in the attenuation curve are diagnosed for the galaxies in our sample. Nevertheless, it is often difficult to ascertain the attenuation law for galaxies in actual observations. Possible reasons for preventing the successful detection of the parameters in the attenuation curve are also discussed in this paper, including the degeneracy of the linear background and the 2175 Å bump in observational channels, the requirement for young and dust-rich systems to study, and the difficulty in accurate estimates of dust attenuations at different wavelength bands.