JWST MIRI Si中的Brighter Fatter效应:作为IBC探测器I.观测、对科学的影响和建模 The Brighter-Fatter Effect in the JWST MIRI Si:As IBC detectors I. Observations, impact on science, and modelling

作者:Ioannis Argyriou Craig Lage George H. Rieke Danny Gasman Jeroen Bouwman Jane Morrison Mattia Libralato Daniel Dicken Bernhard R. Brandl Javier Álvarez-Márquez Alvaro Labiano Michael Regan Michael E. Ressler

詹姆斯·韦伯太空望远镜(JWST)上的中红外仪器(MIRI)使用了三个Si:As杂质带传导(IBC)探测器阵列。每个MIRI探测器像素的输出电压电平通过向上采样斜坡进行数字记录。对于均匀或低对比度照明,像素斜坡以可预测的方式变得非线性,但在高对比度的区域,非线性曲线变得更加复杂。我们在MIRI常规和高对比度coronographic成像、低分辨率光谱和中分辨率光谱数据中提供了Brighter Fatter效应(BFE)的观测证据,并研究了对探测器像素原始电压积分斜坡产生影响的物理机制。我们使用了JWST/MRI调试和循环1阶段的公共数据。我们还使用公共Poisson_CCD代码的修改版本开发了MIRI探测器的静电数值模型。MIRIBFE背后的物理机制与

The Mid-Infrared Instrument (MIRI) on board the James Webb Space Telescope(JWST) uses three Si:As impurity band conduction (IBC) detector arrays. Theoutput voltage level of each MIRI detector pixel is digitally recorded bysampling-up-the-ramp. For uniform or low-contrast illumination, the pixel rampsbecome non-linear in a predictable way, but in areas of high contrast, thenon-linearity curve becomes much more complex. We provide observationalevidence of the Brighter-Fatter Effect (BFE) in MIRI conventional andhigh-contrast coronographic imaging, low-resolution spectroscopy, andmedium-resolution spectroscopy data and investigate the physical mechanism thatgives rise to the effect on the detector pixel raw voltage integration ramps.We use public data from the JWST/MIRI commissioning and Cycle 1 phase. We alsodevelop a numerical electrostatic model of the MIRI detectors using a modifiedversion of the public Poisson_CCD code. The physical mechanism behind the MIRIBFE is fundamentally different to that of CCDs and Hawaii-2RG (H2RG) detectors.This is due to the largest majority of the MIRI photo-excited electric chargesnot being stored at the pixels but at the input to the MIRI detector unit cellbuffer amplifier capacitance. The resulting detector voltage debiasing altersthe electrostatic potential inside the infrared-active layer and causes newphoto-excited electrons, generated at a bright pixel, to be guided to theneighboring fainter pixels. Observationally, the debiasing-induced BFE makesthe JWST MIRI data yield 10-25 % larger and 0.5-8 % brighter point sources andspectral line profiles as a function of the output level covered by thedetector pixels. We find that the profile of the shrinking detector depletionregion has implications for developing a pixel ramp non-linearity model forpoint sources observed with MIRI.



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