Description
This work investigates how the lensing signature and detectability of dark matter subhalos in mock HST and Euclid-like strong lensing observations depends on the subhalo's radial density profile, especially with regards to the inner power-law slope, $\beta$. The inner region of a subhalo's density distribution is particularly sensitive to dark matter microphysics, with alternative dark matter models leading to both cored ($\beta \sim 0.0$) and very steep inner density profiles ($\beta > 2.0$). We demonstrate that the minimum-mass subhalo detectable along the Einstein ring of a system is strongly dependent on $\beta$. We find that subhalos with $\beta \sim 2.2$ (resembling core-collapsed subhalos that can arise from dark matter self interactions) can be detected down to halo masses approximately an order-of-magnitude lower than their NFW counterparts. We also demonstrate how accurately one can infer $\beta$ and distinguish cored versus steep inner density slopes from lensing observations. The results of this work highlight how strong lensing subhalo detections, or lack-thereof, may aid in dark matter constraints, particularly pertaining to models such as SIDM, which predict the existence of subhalos with very steep inner density profiles.
