Searching for dark matter substructure: a deeper wide-area community survey for Roman

TL;DR

This paper proposes a deeper extension to the Roman Space Telescope's survey to detect and analyze dark matter substructure through gravitational lensing, aiming to identify around 500 high-quality lenses for dark matter research.

Contribution

It introduces a strategic survey extension optimized for dark matter substructure detection, significantly increasing the number of characterizable gravitational lenses.

Findings

Expected to find ~500 strong lenses with substructure per survey tile.

Roman will outperform current telescopes in characterizing dark matter subhalos.

The survey will target dark matter subhalos in the mass range 10^7-10^11 M_sun.

Abstract

We recommend a deeper extension to the High-Latitute Wide Area Survey planned to be conducted by the Nancy Grace Roman Space Telescope (\emph{Roman}). While this deeper-tier survey extension can support a range of astrophysical investigations, it is particularly well suited to characterize the dark matter substructure in galactic halos and reveal the microphysics of dark matter through gravitational lensing. We quantify the expected yield of \emph{Roman} for finding galaxy-galaxy-type gravitational lenses and motivate observational choices to optimize the \emph{Roman} core community surveys for studying dark matter substructure. In the proposed survey, we expect to find, on average, one strong lens with a characterizable substructure per \emph{Roman} tile (0.28 squared degrees), yielding approximately 500 such high-quality lenses. With such a deeper legacy survey, \emph{Roman} will outperform any current and planned telescope within the next decade in its potential to characterize the concentration and abundance of dark matter subhalos in the mass range 10$^7$-10$^{11}$\,M$_{\odot}$.