Simulated Early Type Galaxies

We created various ensemble simulated images, to extensively test various aspects of GALPHAT under a variety of circumstances: (1) varying $r_{e}$ and the shape parameter $n$ as a function of S/N and PSF FWHM (Ensemble A); (2) varying the position angle (PA) and $n$ as function of PSF FWHM, and assuming typical values for $r_{e}$, $q$ and S/N (Ensemble B); (3) varying the axis ratio $q$ as function of PSF FWHM, $n$ and considering typical values for S/N and $r_{e}$ (Ensemble C); (4) varying $n$ and PSF FWHM, for a comparison between GALPHAT and GALFIT (Ensemble D); (5) galaxies with a real distribution of ETG structural parameters based on the SPIDER project (Ensemble E); and (6) galaxies with central point sources to test the Bayes-factor model classification as a indicator of nuclear activity assuming typical PSF FWHM and S/N (Ensemble F). <br> [1]La Barbera, F., de Carvalho, R. R., de La Rosa, I. G., Lopes, P. A. A., Kohl-Moreira, J. L., and Capelato, H. V., “SPIDER - I. Sample and galaxy parameters in the grizYJHK wavebands”, <i>Monthly Notices of the Royal Astronomical Society</i>, vol. 408, no. 3, pp. 1313–1334, 2010. doi:10.1111/j.1365-2966.2010.16850.x <br> <br>

我们构建了多组集成模拟图像，以在多种实验条件下全面测试GALPHAT的各项性能指标：<br>(1) 以信噪比（Signal-to-Noise Ratio, S/N）和点扩散函数半高全宽（Point Spread Function Full Width at Half Maximum, PSF FWHM）为变量，调整有效半径$r_e$与形状参数$n$（集成数据集A）；<br>(2) 以点扩散函数半高全宽为变量，调整位置角（Position Angle, PA）与形状参数$n$，并采用有效半径$r_e$、轴比$q$与信噪比的典型取值（集成数据集B）；<br>(3) 以点扩散函数半高全宽与形状参数$n$为变量，调整轴比$q$，并采用信噪比与有效半径$r_e$的典型取值（集成数据集C）；<br>(4) 调整形状参数$n$与点扩散函数半高全宽，用于GALPHAT与GALFIT的性能对比（集成数据集D）；<br>(5) 基于SPIDER项目的早型星系（Early-Type Galaxies, ETG）结构参数真实分布构建的星系样本（集成数据集E）；<br>(6) 包含中心点源的星系样本，采用典型的点扩散函数半高全宽与信噪比取值，以贝叶斯因子（Bayes-factor）模型分类结果作为核活动指示物开展测试（集成数据集F）。<br>[1] La Barbera F, de Carvalho R R, de La Rosa I G, Lopes P A A, Kohl-Moreira J L, Capelato H V. SPIDER——Ⅰ：grizYJHK波段的样本与星系参数[J]. 皇家天文学会月报, 2010, 408(3): 1313–1334. DOI:10.1111/j.1365-2966.2010.16850.x<br><br>