Strong Lensing by Subhalos in the Dwarf-Galaxy Mass Range II: Detection Probabilities

Understand

The dark halo substructures predicted by current cold dark matter simulations may in principle be detectable through strong-lensing image splitting of quasars on small angular scales (0.01 arcseconds or below).

• Here, we estimate the overall probabilities for lensing by substructures in a host halo closely aligned to the line of sight to a background quasar.
• Under the assumption that the quasar can be approximated as a point source, the optical depth for strong gravitational lensing by subhalos typically turns out to be very small (tau < 0.01), contrary to previous claims.
• We therefore conclude that it is currently not feasible to use this strategy to put the simulation predictions for the dark matter subhalo population to the test.