用神经网络加速天文星体耀斑检测的贝叶斯建模,大幅降低计算开销。
Scalable Bayesian Additive Models for Stellar Flare Detection via Amortized Gaussian Process Inference and Hidden Markov Models
- 用变分自编码器学习高斯过程先验的低维表示,替代复杂协方差计算。
- 在模拟和真实数据上验证,该方法保留了原始模型的结构精度。
- 可扩展至大规模星体时间序列,适合处理海量天文观测数据。
高斯过程(GPs)是贝叶斯时间序列建模的强大工具,但其立方级计算复杂度严重制约了其在长时序、高采样率天文数据中的应用。尽管专用高效求解器如Celerite将复杂度降至线性,但在迭代贝叶斯采样中重复计算精确似然仍是构建更复杂模型(如层次或加法模型)的瓶颈,此时Celerite仅是其中一部分。为解决此问题,我们提出一种生成式代理框架:通过变分自编码器(VAE)学习Celerite先验的压缩表示,将高度相关的随机依赖关系映射到低维各向同性流形。该转换完全绕过精确协方差运算,将计算负担转移到快速神经网络前向传播。通过大规模模拟研究,我们证明该代理框架准确复现了像Celerite这类精确物理核的结构保真度。最后,我们将VAE近似嵌入一个结合Celerite与隐马尔可夫模型(HMM)的加法模型,用于恒星耀斑检测。在实测天体时间序列上,我们对比了联合VAE+HMM架构与精确的Celerite+HMM框架,结果表明所提方法显著降低计算时间,实现了对大规模数据档案中恒星耀斑的严格、大范围特征刻画。
原文摘要 · Abstract (English)
Gaussian Processes (GPs) are a powerful tool for Bayesian time-series modeling, yet their cubic computational cost remains a severe barrier for application to long, high-cadence datasets in astronomy. While specialized scalable solvers like Celerite elegantly reduce this scaling to linear time, repeatedly evaluating the exact likelihood during iterative Bayesian sampling is a bottleneck for developing more complex models, like hierarchical or additive models in which Celerite is only one component. To make this inference computationally tractable, we introduce a generative surrogate framework. By utilizing a Variational Autoencoder (VAE) to learn a compressed representation of the Celerite prior, we map highly correlated stochastic dependencies into a low-dimensional, isotropic manifold. This transition completely bypasses exact covariance operations, shifting the computational burden to a rapid neural network forward pass. Through an extensive simulation study, we show that the generative surrogate accurately reproduces the structural fidelity of exact physical kernels like Celerite. Finally, we demonstrate embedding our VAE approximation into an additive model that combines Celerite and a hidden Markov model (HMM) for stellar flare detection in time series data of stars. We evaluate the joint VAE+HMM architecture against the exact Celerite+HMM framework on empirical astrophysical time series and demonstrate that the proposed methodology achieves significant reductions in computational time, enabling the rigorous, large-scale characterization of stellar flares across massive data archives.
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