发表机构
University of Maryland, Baltimore County; NASA Goddard Space Flight Center; Center for Research and Exploration in Space Science and Technology; Space Telescope Science Institute（马里兰大学巴尔的摩县分校; 美国国家航空航天局戈达德太空飞行中心; 空间科学与技术研究探索中心; 太空望远镜科学研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
针对罗曼太空望远镜WFI探测器，利用塔尔博特效应表征亮-胖效应，发现像素有效面积随电荷对比度线性减小，并提出基于平场IPNL的校正方法，将效应降低约25倍。
AI 中文摘要
南希·格雷斯·罗曼太空望远镜将利用其宽视场仪器（WFI）开展多项由社区驱动的巡天项目，该仪器的焦平面上装有18个Teledyne H4RG-10近红外探测器。罗曼望远镜用于测量弱引力透镜的大面积巡天对WFI的点扩散函数（PSF）精度提出了特别严格的要求。亮-胖效应（BFE）是一种非线性探测器效应，由曝光过程中新产生的电荷偏离已累积电荷的像素所致。因此，在探测器上测得的PSF取决于像素间的电荷对比度，从而天文源的有效PSF是流量对比度和积分时间的函数。我们通过在NASA戈达德太空飞行中心探测器表征实验室使用塔尔博特照明器将一组亮点点源网格投射到非飞行件H4RG探测器上，展示了对该探测器上观测到的BFE的表征。我们发现，像素的有效面积随其与相邻像素的电荷对比度每电子减少$(-2.18\pm0.04) \times 10^{-6}$，这对应于在曝光过程中有效PSF尺寸的可测量增加。尽管存在电荷迁移，亮源附近检测到的总信号大致守恒。我们还分析了同一探测器的平场统计，以测量总像素间非线性（IPNL），该非线性主要由BFE主导。我们提出了一种利用平场IPNL结果校正H4RG图像中BFE的方法，该方法改编自现有的光学校正技术。该校正将观测到的BFE（以有效像素面积变化衡量）降低了约25倍，但校正后的数据中仍存在残余非线性。我们讨论了残余非线性的可能来源，并提出了在罗曼巡天图像中研究最优BFE校正的途径。
英文摘要
The Nancy Grace Roman Space Telescope will conduct several community-driven surveys using its Wide Field Instrument (WFI), which contains 18 Teledyne H4RG-10 near-infrared detectors in the focal plane. Roman's wide area survey to measure weak gravitational lensing places particularly stringent requirements on point spread function (PSF) precision for the WFI. The brighter-fatter effect (BFE) is a nonlinear detector effect caused by the deflection of new charge away from pixels with previously accumulated charge during an exposure. As a result, the PSF measured at the detector depends on the charge contrast between pixels, and therefore the effective PSF for astronomical sources is a function of flux contrast and integration time. We present characterization of the BFE observed in a non-flight H4RG by projecting a grid of bright point sources onto the detector using the Talbot Illuminator at the NASA Goddard Space Flight Center Detector Characterization Lab. We find that the effective area of a pixel decreases by $(-2.18\pm0.04) \times 10^{-6}$ per electron of charge contrast with its neighbors, corresponding to a measurable increase in the effective PSF size over the course of an exposure. Despite charge migration, the total signal detected in the vicinity of a bright source is roughly conserved. We also analyze flat field statistics for the same detector to measure the total inter-pixel nonlinearity (IPNL), which is dominated by BFE. We present a method to correct BFE in H4RG images using the flat field IPNL results, adapted from an extant optical correction technique. The correction reduces the observed BFE by about a factor of 25 as measured by the effective pixel area change, but there is remaining nonlinearity in the corrected data. We discuss possible sources of residual nonlinearity and suggest avenues to investigate optimal BFE correction in Roman survey images.
Comments16 pages, 13 figures, submitted to PASP
