How Well Can We Measure the Stellar Mass of a Galaxy: The Impact of the Assumed Star Formation History Model in SED Fitting
How Well Can We Measure the Stellar Mass of a Galaxy: The Impact of the Assumed Star Formation History Model in SED Fitting
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DOI：
10.3847/1538-4357/abbfa7
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发表时间：
2020-06
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影响因子：
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通讯作者：
S. Lower;D. Narayanan;J. Leja;Benjamin D. Johnson;C. Conroy;R. Dav'e
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作者：
S. Lower;D. Narayanan;J. Leja;Benjamin D. Johnson;C. Conroy;R. Dav'e
推断星系恒星质量（M *）的主要方法是通过光谱能量分布（SED）模型。然而，该技术依赖于诸如星系恒星形成历史（SFH）和尘埃衰减定律等假设，这些假设可能严重影响SED建模所得物理性质的准确性。在这里，我们研究了假设的SFH对SED拟合推断出的恒星特性的影响，通过对高分辨率宇宙流体动力学星系形成模拟的模拟观测进行地面验证。传统上，SFHs是用简化的参数化函数形式建模的，但这些形式不太可能捕捉到星系SFHs的真正多样性，并且可能会对结果造成系统偏差和未被充分报告的不确定性。我们证明了灵活的非参数SFHs在捕获星系SFHs变化方面优于传统的参数形式，因此，在SED拟合中显著改善了恒星质量。我们发现，对于非参数模型，延迟-τ模型的平均偏差从0.4个指数下降到0.1个指数以下，尽管这在很大程度上取决于非参数模型的先验选择。类似地，在SED拟合中使用非参数SFHs可以提高恢复星系恒星形成率和恒星年龄的准确性。
The primary method for inferring the stellar mass (M *) of a galaxy is through spectral energy distribution (SED) modeling. However, the technique rests on assumptions such as the galaxy star formation history (SFH) and dust attenuation law that can severely impact the accuracy of derived physical properties from SED modeling. Here we examine the effect that the assumed SFH has on the stellar properties inferred from SED fitting by ground-truthing them against mock observations of high-resolution cosmological hydrodynamic galaxy formation simulations. Classically, SFHs are modeled with simplified parameterized functional forms, but these forms are unlikely to capture the true diversity of galaxy SFHs and may impose systematic biases with underreported uncertainties on results. We demonstrate that flexible nonparametric SFHs outperform traditional parametric forms in capturing variations in galaxy SFHs and, as a result, lead to significantly improved stellar masses in SED fitting. We find a decrease in the average bias of 0.4 dex with a delayed-τ model to a bias under 0.1 dex for the nonparametric model, though this is heavily dependent on the choice of prior for the nonparametric model. Similarly, using nonparametric SFHs in SED fitting results in increased accuracy in recovered galaxy star formation rates and stellar ages.