用光度数据联合推断超新星本质属性与宇宙学参数,提升精度四倍。
CIGaRS I: Combined simulation-based inference from type Ia supernovae and host photometry
- 构建统一贝叶斯模型,从光度数据反推超新星亮度与宿主星系关系
- 模拟显示金属丰度和年龄对亮度有明显观测特征,金属丰度对应质量约10¹⁰M☉的亮度突变
- 可实现精确光度红移(中位误差~0.01),并使宇宙学约束精度提升4倍
利用Ia型超新星作为宇宙学探针需对宿主环境相关的观测偏差进行校正。本文提出一种统一的贝叶斯分层模型,仅基于光度观测即可同时推断:Ia型超新星本征亮度与前身星性质(金属丰度与年龄)的关系、按年龄变化的延迟时间分布、宇宙学参数以及所有宿主星系的红移。模型融合了Prospector-beta提供的恒星形成与化学演化物理模型、星系及超新星光尘消光机制,以及观测选择效应。模拟表明,金属丰度与年龄对亮度的影响具有明确观测信号,其中金属丰度效应在宿主星系恒星质量约10¹⁰M☉处表现为明显的亮度台阶。我们进一步展示了对约16,000个Ia型超新星及其宿主星系的模拟观测数据进行神经网络驱动的仿真推断,结果表明该联合物理模型能提供稳健且高精度的光度红移(中位散度~0.01),并将宇宙学约束精度相比仅依赖少数光谱确认样本的分析方法提升约4倍。该方法充分释放了光度数据潜力,为未来大规模巡天(如LSST)时代的端到端仿真推断流程奠定基础。
原文摘要 · Abstract (English)
Using type Ia supernovae as cosmological probes requires empirical corrections that are correlated with their host environment. Here we present a unified Bayesian hierarchical model designed to infer, from purely photometric observations, the intrinsic dependence of the brightness of type Ia supernovae on progenitor properties (metallicity and age), the delay-time distribution that governs their rate as a function of age, and cosmology, as well as the redshifts of all hosts. The model incorporates physics-based prescriptions for star formation and chemical evolution from Prospector-beta, dust extinction of both galaxy and supernova light, and observational selection effects. We show with simulations that intrinsic dependences on metallicity and age have distinct observational signatures, with metallicity mimicking the well-known step of magnitudes of type Ia supernovae across a host stellar mass of $\sim 10^{10}M_{\odot}$. We then demonstrate neural simulation-based inference of all model parameters from mock observations of ~16,000 type Ia supernovae and their hosts up to redshift 0.9. Our joint physics-based approach delivers robust and precise photometric redshifts (~0.01 median scatter) and improves cosmological constraints by a factor of ~4 over analyses of the small fraction of objects with spectroscopic follow-up. This approach unlocks the full power of photometric data and paves the way for an end-to-end simulation-based analysis pipeline in the LSST era.
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