论文标题
Ultracool矮人的均匀前向模型分析。 I.方法论和基准测试
Uniform Forward-Modeling Analysis of Ultracool Dwarfs. I. Methodology and Benchmarking
论文作者
论文摘要
我们使用贝叶斯推理工具海星和无云的Sonora-Bobcat模型氛围提出了一个向前模型的框架，以分析近红外（$ 1.0-2.5 $ $ $ $ $ $ M）的低分辨率（$ r \ of of \ r \ of of 80-250 $）。我们的方法渗透有效的温度，表面重力，金属性，半径和质量，并通过对模型插值的不确定性和由于工具效应和建模系统的相关残差而产生的不确定性比传统的（$χ^2 $ - 基于基于基于$χ^2 $ - 基于基于的）光谱分析产生更真实的参数后代。我们通过拟合模型大气并在派生和输入参数之间找到可忽略的偏移来验证我们的框架。我们使用太阳能和非极性金属性大气模型都将方法应用于三个众所周知的基准后期T小矮人，HD 3651B，GJ 570D和Ross 458C。我们还使用其辐射仪，主要恒星的年龄和金属性以及Sonora-Bobcat进化模型来得出这些基准的物理特性。假设基于进化的参数更鲁棒，我们发现我们的基于大气的前向模型分析会产生两个结果。对于HD 3615b和GJ 570D，频谱拟合提供准确的$ t _ {\ rm eff} $和$ r $，但低估了$ \ log {g} $（$ \ of $ \ of1.2 $ dex）和$ z $（可能是$ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ of \ \ of0.35 $ dex）。对于Ross 458C，频谱拟合提供准确的$ \ log {g} $和$ z $，但被高估了$ t _ {\ rm eff} $（由$ \ of $ \ of120 $ k），而被低估的$ r $（$ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ y \ y ock1.6 \ times $）低约1.6 \ times $，因为我们的模型大气不足云的垂直级别，或者是vertical vertical disefible，或者逐渐缩小。最后，这些基准的光谱推断质量都被大大低估了。
We present a forward-modeling framework using the Bayesian inference tool Starfish and cloudless Sonora-Bobcat model atmospheres to analyze low-resolution ($R\approx80-250$) near-infrared ($1.0-2.5$ $μ$m) spectra of T dwarfs. Our approach infers effective temperatures, surface gravities, metallicities, radii, and masses, and by accounting for uncertainties from model interpolation and correlated residuals due to instrumental effects and modeling systematics, produces more realistic parameter posteriors than traditional ($χ^2$-based) spectral-fitting analyses. We validate our framework by fitting the model atmospheres themselves and finding negligible offsets between derived and input parameters. We apply our methodology to three well-known benchmark late-T dwarfs, HD 3651B, GJ 570D, and Ross 458C, using both solar and non-solar metallicity atmospheric models. We also derive these benchmarks' physical properties using their bolometric luminosities, their primary stars' ages and metallicities, and Sonora-Bobcat evolutionary models. Assuming the evolutionary-based parameters are more robust, we find our atmospheric-based, forward-modeling analysis produces two outcomes. For HD 3615B and GJ 570D, spectral fits provide accurate $T_{\rm eff}$ and $R$ but underestimated $\log{g}$ (by $\approx1.2$ dex) and $Z$ (by $\approx0.35$ dex), likely due to the systematics from modeling the potassium line profiles. For Ross 458C, spectral fits provide accurate $\log{g}$ and $Z$ but overestimated $T_{\rm eff}$ (by $\approx120$ K) and underestimated $R$ (by $\approx1.6\times$), likely because our model atmospheres lack clouds, reduced vertical temperature gradients, or disequilibrium processes. Finally, the spectroscopically inferred masses of these benchmarks are all considerably underestimated.
