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arXiv 2201.05285astro-ph.GA
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复合材料Galerkin SED拟合参数估计的系统性

Systematics in the SED Fitting Parameter Estimation of Composite Galaxies

Katherine Zine, Samir Salim

摘要:

利用光谱能量分布(SED)拟合推导星系的物理性质是一种有效的方法,但会受到模型假设所产生的各种系统学的影响。以前,这种偏差主要是在单个星系的背景下研究的。在这项研究中,我们调查潜在的偏见所产生的执行SED拟合两个星系的组合光,合并后的系统的情况下。我们使用GALEX-SDSS-WISE Legacy Catalog(GSWLC)的z<0.3星系来识别9,000个最终可能合并的星系对。对于这些,我们调查,如果UV/光学SED拟合准确地确定恒星质量和(特定)恒星形成率,如果对未解决(合并)。这对星系中单个星系的恒星质量(和SFR)之和为这些量建立了基础事实。对于恒星形成星系,恒星质量、SFR或sSFR没有偏差(<0.1 dex)。SFR(~0.1 dex)中的中等系统性被发现的系统与两个星系之间的尘埃含量的极端对比。我们的结论是,会出现的偏见,在确定质量和SFR的合并后系统的帐户的两个原始星系有可能非常不同的恒星形成历史和不同的尘埃属性是小的,简单的两个组件的恒星形成历史的方法是足够的。在这项研究中提出的方法,使用通量合成与经验确定的地面真相,提供了新的机会,测试结果的SED拟合一般。

英文摘要:

Derivation of physical properties of galaxies using spectral energy distribution (SED) fitting is a powerful method, but can suffer from various systematics arising from model assumptions. Previously, such biases were mostly studied in the context of individual galaxies. In this study, we investigate potential biases arising from performing the SED fitting on the combined light of two galaxies, as would be the case in post-merger systems. We use GALEX-SDSS-WISE Legacy Catalog (GSWLC) of z<0.3 galaxies to identify 9,000 galaxy pairs that could eventually merge. For these we investigate if the UV/optical SED fitting accurately determines the stellar mass and (specific) star formation rate if the pair was unresolved (merged). The sum of the stellar masses (and SFRs) of individual galaxies in the pair establishes the ground truth for these quantities. For star forming galaxies no biases (<0.1 dex) are found in the stellar mass, SFR, or sSFRs. Moderate systematics in SFR (~0.1 dex) are found for systems with an extreme contrast in dust content between the two galaxies. We conclude that biases that would arise in the determination of masses and SFRs of post-merger systems on account of the two original galaxies having potentially very different star formation histories and different dust properties are small and that the approach with simple two-component star formation histories is adequate. The approach presented in this study, using flux compositing with empirically determined ground truth, offers new opportunities for testing the results of SED fitting in general.

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