Strongly lensed cluster substructures are not in tension with
  $\Lambda$CDM
  Strong gravitational lensing observations can test structure formation models
by constraining the masses and concentrations of subhaloes in massive galaxy
clusters. Recent work has concluded that cluster subhaloes are more abundant
and/or concentrated than predicted by $\Lambda$CDM simulations; this finding
has been interpreted as arising from unidentified issues with simulations or an
incorrect understanding of the nature of dark matter. We test these hypotheses
by comparing observed subhalo masses and maximum circular velocities
$v_\mathrm{max}$ to predictions from the high resolution Hydrangea galaxy
cluster simulation suite, which is based on the successful EAGLE galaxy
formation model. The simulated subhalo mass distribution and
mass-$v_\mathrm{max}$ relation agrees well with observations, due to the
presence of baryons during tidal stripping. Similar agreement is found for the
lower-resolution Illustris-TNG300 simulation. In combination, our results
suggest that the abundance and concentration of cluster substructures are not
in tension with $\Lambda$CDM, but may provide useful constraints for the
refinement of baryon physics models in simulations.
