GASPHOT: a tool for Galaxy Automatic Surface PHOTometry
GASPHOT: a tool for Galaxy Automatic Surface PHOTometry
复制标题
GASPHOT：Galaxy 自动表面测光工具
DOI：
10.1051/0004-6361:20041704
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发表时间：
2001
影响因子：
6.5
通讯作者：
P. Cassata
中科院分区：
文献类型：
--
作者：
E. Pignatelli;G. Fasano;P. Cassata
在这篇文章中，我们提出了一种新的工具，用于对深部和/或宽视场的星系进行自动、盲表面光度测量。该工具(GASPHOT)支持与星系建模细节相关的结果的稳健性。为此，对模型采用单一的Seric定律，对最佳拟合算法采用一维/二维混合方法。GASPHOT在很大程度上是基于SExtractor的，它提供了从CCD图像中提取的星系的光度、位置角和椭圆度轮廓，以及总星等、半光半径和Seric指数。这些整体参数是通过同时用二维平坦的Sersic定律拟合星系的长轴和短轴光生长曲线来获得的，该定律由适当的空间变化的PSF卷积而成，该PSF之前由该工具本身评估。我们在15000多个模拟和真实的星系上进行了GASPHOT测试，获得了星系整体参数误差的可靠上限，即使是对于非Seric轮廓和混合体。GASPHOT的性能还与两种流行的单一组件替代工具Sersic Law的性能进行了比较：GALFIT(Peng等人)。2002)和GIM2D(Marleau&Simard 1998)。当处理理想的、孤立的和非常大的星系时，除了在GIM2D星等上有一定的偏差外，这三个包都被发现提供了令人满意的结果。另一方面，对于模拟的混合物体和真实的星系，GASPHOT被证明比GALFIT和GIM2D更稳健。此外，与GASPHOT和GALFIT不同的是，GIM2D提供的拟合质量(偏差和散射)随着星系大小的减小而迅速下降。
In this paper we present a new tool for automatic, blind surface photometry of galaxies in deep and/or wide fields. The tool (GASPHOT) favors the robustness of results with respect to the details of galaxy modeling. To this aim, a single Sersic-law for the models and a hybrid 1D/2D approach for the best-fitting algorithm were adopted. GASPHOT is heavily based on SExtractor and provides luminosity, position angle and ellipticity profiles of galaxies extracted from CCD frames, as well as total magnitudes, half-light radii, and Sersic indices. These global parameters were obtained by simultaneously fitting the major and minor axis light growth curves of galaxies with a 2D flattened Sersic-law, convolved by the appropriate, space-varying PSF, which was previously evaluated by the tool itself. We tested GASPHOT on more than 15 000 simulated and real galaxies, obtaining robust upper limits for the errors of the global parameters of galaxies, even for non-Sersic profiles and blended objects. The GASPHOT performance was also compared with those of two popular alternative tools for a single component, Sersic law: GALFIT (Peng et al. 2002) and GIM2D (Marleau & Simard 1998). When dealing with ideal, isolated, and adeguately large galaxies, the three packages were all found to provide satisfactory results, apart from a definite bias in the GIM2D magnitudes. On the other hand, GASPHOT proved to be more robust than GALFIT and GIM2D for simulated, blended objects and for real galaxies. Moreover, at variance with GASPHOT and GALFIT, the quality (bias and scatter) of the fits provided by GIM2D rapidly declines as the galaxy size decreases.