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arXiv 1709.00746astro-ph.GAastro-ph.IM
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一种精确的圆盘Galerkin凸度-圆盘分解的优化策略

An Optimal Strategy for Accurate Bulge-to-disk Decomposition of Disk Galaxies

Hua Gao, Luis C. Ho

摘要:

二维(2D)球盘分解技术的发展已经显示出其优于传统的一维(1D)技术,特别是对于具有非轴对称特征的星系。然而,2D技术的全部潜力尚未得到充分开发。在附近的盘状星系,如酒吧,透镜,环,磁盘断裂,和螺旋臂,次要的形态特征,很少占在二维图像分解,即使一些图像拟合代码,如GALFIT,能够处理它们。我们提出了详细的,2D多模型和多组件分解的高品质的$R$波段图像的代表性样本附近的盘星系从伯奇-欧文星系调查,使用最新版本的GALFIT。样本包括五个酒吧和五个unbarred星系,跨越哈勃类型从S 0到Sc。传统的一维分解也进行了比较。在10个星系的详细案例研究中,我们成功地模拟了次级形态特征。通过比较从不同输入表面亮度模型获得的最佳拟合参数,我们确定了显着影响凸起测量的形态特征。我们表明,核和内部的透镜/环和磁盘断裂必须适当考虑,以获得准确的凸起参数,而外部的透镜/环和螺旋臂有一个可以忽略不计的影响。我们提供了一个最佳的策略来测量典型的盘星系的隆起参数,以及处方,以估计它们的现实不确定性,这将有利于后续分解的一个更大的星系样本。

英文摘要:

The development of two-dimensional (2D) bulge-to-disk decomposition techniques has shown their advantages over traditional one-dimensional (1D) techniques, especially for galaxies with non-axisymmetric features. However, the full potential of 2D techniques has yet to be fully exploited. Secondary morphological features in nearby disk galaxies, such as bars, lenses, rings, disk breaks, and spiral arms, are seldom accounted for in 2D image decompositions, even though some image-fitting codes, such as GALFIT, are capable of handling them. We present detailed, 2D multi-model and multi-component decomposition of high-quality $R$-band images of a representative sample of nearby disk galaxies selected from the Carnegie-Irvine Galaxy Survey, using the latest version of GALFIT. The sample consists of five barred and five unbarred galaxies, spanning Hubble types from S0 to Sc. Traditional 1D decomposition is also presented for comparison. In detailed case studies of the 10 galaxies, we successfully model the secondary morphological features. Through a comparison of best-fit parameters obtained from different input surface brightness models, we identify morphological features that significantly impact bulge measurements. We show that nuclear and inner lenses/rings and disk breaks must be properly taken into account to obtain accurate bulge parameters, whereas outer lenses/rings and spiral arms have a negligible effect. We provide an optimal strategy to measure bulge parameters of typical disk galaxies, as well as prescriptions to estimate realistic uncertainties of them, which will benefit subsequent decomposition of a larger galaxy sample.

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