A synthetic <i>Roman Space Telescope</i> High-Latitude Imaging Survey: simulation suite and the impact of wavefront errors on weak gravitational lensing

Troxel, M. A.; Long, Heyang; Hirata, Christopher M.; Choi, A.; Jarvis, Mike; Mandelbaum, Rachel; Wang, Will Ke; Yamamoto, Masaya; Hemmati, Shoubaneh; Capak, P.

doi:10.1093/mnras/staa3658

Cited by 28 publications

(30 citation statements)

References 62 publications

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“…(Note that there are some noise fluctuations in this map due to the modest number of pixels being averaged; however the correlation function ξ ± (θ) remains unbiased in the presence of these noise fluctuations.) Troxel et al (2021) can be carried over to our case. In the worst-affected redshift bin, the shear error induced by charge diffusion is…”

Section: Impact Of Charge Diffusion On the Shear Signalmentioning

confidence: 94%

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Quantum Yield and Charge Diffusion in the Nancy Grace Roman Space Telescope Infrared Detectors

Givans

Choi

Porredon

et al. 2022

PASP

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Weak gravitational lensing is a powerful tool for studying the growth of structure across cosmic time. The shear signal required for weak lensing analyses is very small, so any undesirable detector-level effects which distort astronomical images can significantly contaminate the inferred shear. The Nancy Grace Roman Space Telescope (Roman) will fly a focal plane with 18 Teledyne H4RG-10 near-infrared (IR) detector arrays; these have never before been used for weak lensing and they present different instrument calibration challenges relative to charge-coupled devices. A pair of previous investigations demonstrated that spatiotemporal correlations of flat field images can effectively separate the brighter-fatter effect (BFE) and interpixel capacitance (IPC). A third paper in the series introduced a Fourier-space treatment of these correlations which allowed the authors to expand to higher orders in BFE, IPC, and classical nonlinearity. This work expands the previous formalism to include quantum yield and charge diffusion. We test the updated formalism on simulations and show that we can recover input visible characterization values to within a few percent. We then apply the formalism to visible and IR flat field data from three Roman flight candidate detectors. We find that BFE is present in all detectors and that the magnitude of its central pixel value is comparable between visible data and IR data. We fit a 2D Gaussian model to the charge diffusion at 0.5 μm wavelength, and find variances of C 11 = 0.1066 ± 0.0011 pix2 in the horizontal direction, C 22 = 0.1136 ± 0.0012 pix2 in the vertical direction, and a covariance of C 12 = 0.0001 ± 0.0007 pix2 (stat) for SCA 20829. Last, we convert the asymmetry of the charge diffusion into an equivalent shear signal using the sensitivity coefficients for the Roman survey, and find a contamination of the shear correlation function to be ξ + ∼ 10−6 for each detector. This exceeds Roman’s allotted error budget for the measurement by a factor of  ( 10 ) in power (amplitude squared) but can likely be mitigated through standard methods for fitting the point-spread function (PSF) since for weak lensing applications the charge diffusion can be treated as a contribution to the PSF. Further work considering the impact of charge diffusion and quantum yield on shear measurements will follow once all detectors covering the Roman focal plane are selected.

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Section: Impact Of Charge Diffusion On the Shear Signalmentioning

confidence: 94%

“…where K θθ = 1.432 × 10 −5 mas −2 = 0.1733 pix −2 (Troxel et al 2021, Table B1). Next we pass a list of superpixel indices (converted to arcsec) and shears to TREECORR 20 ) which calculates the shear correlation functions ξ + (θ) and ξ − (θ).…”

Section: Impact Of Charge Diffusion On the Shear Signalmentioning

confidence: 98%

Quantum Yield and Charge Diffusion in the Nancy Grace Roman Space Telescope Infrared Detectors

Givans

Choi

Porredon

et al. 2022

PASP

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“…In this work, we use the image simulation suite developed by Troxel et al (2021). The persistence effect is applied along with other detector effects to test the impact of persistence on galaxy shapes.…”

Section: Image Simulationsmentioning

confidence: 99%

“…Here we highlight the key elements of the simulations, and we refer readers to Troxel et al (2021) for more details.…”

Section: Image Simulationsmentioning

confidence: 99%

“…The image simulation is carried out using the simulation suite developed by Troxel et al (2021), which simulates the stars and galaxies in the input catalog and generates SCA images on 4088 × 4088 pixels stamps. Effects including sky background, reciprocity failure, electron quantization, dark current, nonlinearity, interpixel capacitance and readout noise are included in the image generation (Troxel et al 2021), following the order that each effect physically occurs. Besides these effect, we apply persistence from previous exposures using the model introduced in Sect.…”

Section: Image Simulation Processmentioning

confidence: 99%

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Impact of Image Persistence in the Roman Space Telescope High-Latitude Survey

Lin,

Mandelbaum,

Troxel

et al. 2021

Preprint

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The High Latitude Survey of the Nancy Grace Roman Space Telescope is expected to measure the positions and shapes of hundreds of millions of galaxies in an area of 2220 deg 2 . This survey will provide high-quality weak lensing data with unprecedented systematics control. The Roman Space Telescope will survey the sky in near infrared (NIR) bands using Teledyne H4RG HgCdTe photodiode arrays. These NIR arrays exhibit an effect called persistence: charges that are trapped in the photodiodes during earlier exposures are gradually released into later exposures, leading to contamination of the images and potentially to errors in measured galaxy properties such as fluxes and shapes. In this work, we use image simulations that incorporate the persistence effect to study its impact on galaxy shape measurements and weak lensing signals. No significant spatial correlations are found between the galaxy shape changes induced by persistence. On the scales of interest for weak lensing cosmology, the effect of persistence on the weak lensing correlation function is about two orders of magnitude lower than the Roman Space Telescope additive shear error budget, indicating that the persistence effect is expected to be a subdominant contributor to the systematic error budget for weak lensing with the Roman Space Telescope given its current design.

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The challenge of blending in large sky surveys

Joseph

Sánchez

2021

Nat Rev Phys

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A synthetic Roman Space Telescope High-Latitude Imaging Survey: simulation suite and the impact of wavefront errors on weak gravitational lensing

Cited by 28 publications

References 62 publications

Quantum Yield and Charge Diffusion in the Nancy Grace Roman Space Telescope Infrared Detectors

Quantum Yield and Charge Diffusion in the Nancy Grace Roman Space Telescope Infrared Detectors

Impact of Image Persistence in the Roman Space Telescope High-Latitude Survey

The challenge of blending in large sky surveys

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