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arXiv 2006.03599astro-ph.GA
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我们如何测量星系的恒星质量:假设恒星形成历史模型对SED拟合的影响

How Well Can We Measure the Stellar Mass of a Galaxy: The Impact of the Assumed Star Formation History Model in SED Fitting

Sidney Lower, Desika Narayanan, Joel Leja, Benjamin D. Johnson, Charlie Conroy, Romeel Davé

摘要:

推导星系恒星质量($M_*$)的主要方法是通过光谱能量分布(SED)模型。然而,该技术依赖于假设,如星系恒星形成的历史和尘埃衰减规律,可能会严重影响SED建模导出的物理性质的准确性。在这里,我们研究的效果,假设的恒星形成历史(SFH)的恒星属性推断SED拟合地面truthing他们对模拟观测的高分辨率宇宙流体动力学星系形成模拟。传统上,SFH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SFH的真实多样性,并可能对结果施加系统性偏差和低估的不确定性。我们表明,灵活的非参数恒星形成的历史优于传统的参数形式在捕捉星系恒星形成历史的变化,因此,导致显着改善恒星质量的SED拟合。我们发现,延迟$τ$模型的平均偏差为0.4 dex,非参数模型的平均偏差略低于0.05 dex。同样,使用非参数恒星形成的历史,在SED拟合结果恢复星系恒星形成率(SFR)和恒星年龄的准确性增加。

英文摘要:

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 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 star formation history (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 under-reported uncertainties on results. We demonstrate that flexible nonparametric star formation histories outperform traditional parametric forms in capturing variations in galaxy star formation histories, 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 of just under 0.05 dex for the nonparametric model. Similarly, using nonparametric star formation histories in SED fitting result in increased accuracy in recovered galaxy star formation rates (SFRs) and stellar ages.

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