Going Forward with the Nancy Grace Roman Space Telescope Transient Survey: Validation of Precision Forward-modeling Photometry for Undersampled Imaging

The Nancy Grace Roman Space Telescope (Roman) is an observatory for both wide-field observations and coronagraphy that scheduled launch in the mid 2020's. Part of planned survey a deep, cadenced field or fields enable cosmological measurements with type Ia supernovae (SNe Ia). With pixel scale 0".11, Wide Field Instrument will be undersampled, presenting difficulty precisely subtracting galaxy light underneath SNe. We use simulated data to validate ability forward-model code (such codes are frequently also called "scene-modeling" codes) perform precision supernova photometry SN survey. Our simulation includes over 760,000 image cutouts around SNe host galaxies (~ 10% full-scale survey). To have realistic 2D distribution underlying light, we VELA high-resolution images galaxies. run each set through our forward-modeling which automatically measures time-dependent fluxes. Given assumed inputs perfect model instrument PSFs calibration, find biases at millimagnitude level from this method four red filters (Y106, J129, H158, F184), easily meeting 0.5% inter-filter calibration requirement cutting-edge measurement parameters using Ia. Simulated bluer Z087 filter shows larger ~ 2--3 biases, requirement, but more room improvement. has been released on Zenodo.