Wide-Field Science – Regular
Tansu Daylan / Washington University, PI
The Roman Telescope will offer a unique opportunity to study strong lenses across cosmic time, enabling thorough investigations of the substructure and microphysics of dark matter. For the first time, the discovery images will have the required depth and resolution to perform high-precision measurements. What the Hubble Space Telescope could do on a limited selected sample, Roman will be able to achieve over the entirety of planned surveys. There is currently no realistic set of simulations of strong lenses with Roman, which can undermine the progress towards achieving maximal cosmology from Roman. Therefore, a set of realistic strong lens simulations must be performed in time in order to train and test the strong lensing pipelines that will process the Roman data.
We propose to generate a comprehensive suite of simulated Roman images of realistic strong lenses with substructure, organize a data challenge for the research community to test their detection and characterization pipelines on these data, and develop robust retrieval pipelines to determine the selection functions on the population-level properties of dark matter substructure indicative of its microphysics.
We will produce a detailed and realistic lens population over cosmic time and then generate synthetic Roman data that can be used for training, validation, or survey planning. We will include in our simulations both galaxy-galaxy-type lenses that are optimal for inferring substructure and quasar lenses that can enable other science cases such as time-delay tomography. Using our multiband simulations, we will enable precise determinations of the expected yields of static galaxy-galaxy strong-lenses, strongly-lensed quasars, and supernovae, as well as their population properties. Toward this goal, we will develop a simulation pipeline that accurately incorporates up-to-date detector characteristics of the Wide Field Instrument (WFI) on Roman and a population model for strong lenses informed by the Hubble Space Telescope and DES. Thus, we will help prepare Roman for the operational phase of the mission and enhance the science return of the WFI. Our work will be a Regular Wide Field Science (WFS) effort over two years, from September 2023 to September 2025.
The primary merit of our proposed effort is to facilitate the timely simulation and survey planning to enable optimal detection and characterization of the strong lenses following the launch of Roman. In particular, the early timing of our precursor effort is crucial to deliver a strong-lens simulation pipeline for Roman on time so that subsequent efforts from 2025 to launch can use the simulation pipeline for yield simulations and data reduction pipelines. Accordingly, our proposed effort is especially suited as a precursor effort ~3-4 years before launch.
Our work is especially relevant as a regular WFS effort in this cycle since our simulations will open the path towards designing strong lens surveys with Roman and optimizing other community surveys for ancillary strong lensing science. Therefore, it is a uniquely suited and timely precursor science effort to be optimally completed ~2 years before the launch of Roman.