利用MagAO-X的全物理可微数字孪生模型进行日冕仪图像的正向建模：实验室初步结果
Forward modelling coronagraphic images with a fully physical, differentiable digital twin of MagAO-X: first laboratory results
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中文总结 AI 辅助
本研究提出MagAO-X的全物理可微数字孪生模型，在实验室中实现日冕仪图像正向建模，可低残差复现PSF且无伴星自抵消，为高对比度成像提供新方法。
中文摘要 AI 辅助
高对比度成像数据的后处理依赖于对恒星点扩散函数（PSF）的精确建模。当前技术通过观测多样性（如角向、光谱或偏振多样性）从科学图像本身构建该模型，这可能导致伴星信号的自抵消，并限制观测策略。基于遥测的正向建模则利用观测期间已记录的波前传感器数据构建恒星PSF模型。波前传感器测量相干星光，因此可用于创建仅建模恒星光、不复制伴星非相干光的PSF模型。我们提出了MagAO-X仪器焦平面低阶波前传感器（FLOWFS）和日冕仪科学光束的全物理可微数字孪生模型，该模型在dLux中实现，并通过实验室数据校准。当直接拟合科学图像时，该模型能将日冕仪PSF的精度复现至数据的光子和读出噪声水平。当仅基于FLOWFS遥测进行正向建模时，在5λ/D处残差达到恒星峰值的6×10⁻⁵，比原始对比度低5倍，剩余残差由波前估计从FLOWFS分支转移至模型科学分支的程度决定。在5λ/D处注入峰值对比度为10⁻³的伴星，可被恢复且无明显自抵消。我们讨论了当前正在开发的模型改进方向及向天空验证推进的路径。
英文摘要
Post-processing of high contrast imaging data relies on an accurate model of the stellar point spread function (PSF). Current techniques build this model from the science images themselves, using observational diversity (e.g., angular, spectral or polarimetric diversity), which can cause self-subtraction of the companion signal and constrains the observing strategy. Telemetry-based forward modelling instead builds the stellar PSF model from wavefront sensor data that is already recorded during the observation. The wavefront sensor measures the coherent starlight and can therefore be used to create a PSF model that only models the stellar light and does not reproduce the incoherent light of a companion. We present a fully physical and differentiable digital twin of the focal plane low-order wavefront sensor (FLOWFS) and the coronagraphic science beam of the MagAO-X instrument, implemented in \texttt{dLux}, and calibrate it on laboratory data. When fitted directly to the science images, the model reproduces the coronagraphic PSF down to the photon and read noise floor of the data. When instead forward modelled from the FLOWFS telemetry alone, the residuals reach $6\times10^{-5}$ of the stellar peak at $5\ λ/D$, a factor of 5 below the raw contrast, with the remaining residual set by how well the wavefront estimate transfers from the FLOWFS branch to the science branch of the model. An injected companion at $5\ λ/D$ with a peak contrast of $10^{-3}$ is recovered without measurable self-subtraction. We discuss the model improvements currently under development and the path towards on-sky validation.
