In the next decade, transient searches from the Vera C. Rubin Observatory and the Nancy Grace Roman Space Telescope will increase the sample of known Type Ia supernovae (SNe Ia) from ∼10³ to 10⁵. With this reduction of statistical uncertainties on cosmological measurements, new methods are needed to reduce systematic uncertainties. Characterizing the underlying spectroscopic evolution of SN Ia remains a major systematic uncertainty in current cosmological analyses, motivating a new simulation tool for the next era of SN Ia cosmology: Build Your Own Spectral Energy Distribution (byosed). byosed is used within the SNANA framework to simulate light curves by applying spectral variations to model SEDs, enabling flexible testing of possible systematic shifts in SN Ia distance measurements. We test the framework by comparing a nominal Roman SN Ia survey simulation using a baseline SED model to simulations using SEDs perturbed with byosed, and investigating the impact of ignoring specific SED features in the analysis. These features include semiempirical models of two possible, predicted relationships: between SN ejecta velocity and light-curve observables, and a redshift-dependent relationship between SN Hubble residuals and host-galaxy mass. We analyze each byosed simulation using the SALT2 and BEAMS with Bias Corrections framework, and estimate changes in the measured value of the dark-energy equation-of-state parameter, w. We find a difference of Δw = −0.023 for SN velocity and Δw = 0.021 for redshift-evolving host mass when compared to simulations without these features. By using byosed for SN Ia cosmology simulations, future analyses (e.g., the Rubin and Roman SN Ia samples) will have greater flexibility to constrain or reduce such SN Ia modeling uncertainties.

在接下来的十年中，来自 Vera C. Rubin 天文台和 Nancy Grace Roman 太空望远镜的瞬态搜索将使已知 Ia 型超新星 (SNe Ia) 的样本从~10 ³增加到 10 ⁵。随着宇宙学测量统计不确定性的减少，需要新的方法来减少系统的不确定性。表征 SN Ia 的潜在光谱演化仍然是当前宇宙学分析中的一个主要系统不确定性，为 SN Ia 宇宙学的下一个时代提供了一种新的模拟工具：建立自己的光谱能量分布（byosed）。被遗忘的在 SNANA 框架中，通过将光谱变化应用于 SED 模型来模拟光变曲线，从而能够灵活测试 SN Ia 距离测量中可能的系统偏移。我们通过比较使用基线 SED 模型的名义 Roman SN Ia 调查模拟与使用受byosed干扰的 SED 的模拟来测试框架，并调查在分析中忽略特定 SED 特征的影响。这些特征包括两种可能的预测关系的半经验模型：SN 喷出物速度和光曲线观测值之间的关系，以及 SN 哈勃残差和宿主星系质量之间的红移依赖关系。我们分析每一个使用带有偏置校正框架的 SALT2 和 BEAMS 进行模拟，并估计暗能量状态方程参数w的测量值的变化。与没有这些特征的模拟相比，我们发现SN 速度的差异为 Δ w = -0.023，红移演化的主体质量为Δ w = 0.021。通过将byosed用于SN Ia 宇宙学模拟，未来的分析（例如，Rubin 和Roman SN Ia 样本）将具有更大的灵活性来约束或减少此类SN Ia 建模不确定性。