Simulating image coaddition with the Nancy Grace Roman Space Telescope – II. Analysis of the simulated images and implications for weak lensing
[1];
[3];
[1];
[4];
[3];
- Duke Univ., Durham, NC (United States)
- The Ohio State Univ., Columbus, OH (United States)
- Carnegie Mellon Univ., Pittsburgh, PA (United States)
- NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
- Princeton Univ., NJ (United States); Flatiron Institute, New York, NY (United States)
- Argonne National Laboratory (ANL), Argonne, IL (United States)
- Univ. of Texas at Dallas, Richardson, TX (United States)
- Univ. of Pennsylvania, Philadelphia, PA (United States)
- Univ. of Edinburgh, Scotland (United Kingdom)
- Univ. of Pittsburgh, PA (United States)
One challenge for applying current weak lensing analysis tools to the Nancy Grace Roman Space Telescope is that individual images will be undersampled. Our companion paper presented an initial application of Imcom – an algorithm that builds an optimal mapping from input to output pixels to reconstruct a fully sampled combined image – on the Roman image simulations. In this paper, we measure the output noise power spectra, identify the sources of the major features in the power spectra, and show that simple analytic models that ignore sampling effects underestimate the power spectra of the coadded noise images. We compute the moments of both idealized injected stars and fully simulated stars in the coadded images, and their one- and two-point statistics. We show that the idealized injected stars have root-mean-square ellipticity errors (1–6) × 10-4 per component depending on the band; the correlation functions are ≥2 orders of magnitude below requirements, indicating that the image combination step itself is using a small fraction of the overall Roman second moment error budget, although the fourth moments are larger and warrant further investigation. The stars in the simulated sky images, which include blending and chromaticity effects, have correlation functions near the requirement level (and below the requirement level in a wide-band image constructed by stacking all four filters). We evaluate the noise-induced biases in the ellipticities of injected stars, and explain the resulting trends with an analytical model. We conclude by enumerating the next steps in developing an image coaddition pipeline for Roman.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC); National Aeronautics and Space Administration (NASA); Simons Foundation; David & Lucile Packard Foundation
- Grant/Contract Number:
- AC02-06CH11357
- OSTI ID:
- 2476165
- Journal Information:
- Monthly Notices of the Royal Astronomical Society, Journal Name: Monthly Notices of the Royal Astronomical Society Journal Issue: 4 Vol. 528; ISSN 0035-8711
- Publisher:
- Oxford University PressCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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