The Roman Survey for Gravitational Lenses Across Cosmic Time

Galaxy-galaxy strong gravitational lenses have strong potential to refine the Lambda Cold Dark Matter cosmological paradigm. Currently, there is a dearth of images of these rare systems with high signal-to-noise and angular resolution. The Nancy Grace Roman Space Telescope, scheduled for launch in late 2026, is expected to play a transformative role in strong lensing. With its remarkable 0.281 square degree wide field of view and diffraction-limited angular resolution of 0.11 arcsec, Roman is uniquely suited to characterizing dark matter substructure from a robust population of gravitational lenses. However, simulating, analyzing, and modeling these images requires novel approaches to image processing and statistical inference that are optimized for performance and efficiency. We recently simulated a population of galaxy-galaxy strong lenses with substructure across cosmic time and estimated the yield of strong gravitational lenses in Roman’s planned High Latitude Wide Area Survey (HLWAS), taking into account realistic Wide Field Instrument detector effects. For a fiducial case of single 146-second exposures, we predict over 100,000 detectable strong lenses in the HLWAS, of which about 500 will have sufficient signal-to-noise to be amenable to detailed substructure characterization. Our simulation products are available to support strong lens science with Roman, such as training neural networks and validating dark matter substructure analysis pipelines.