The lensing properties of subhaloes in massive elliptical galaxies in
  sterile neutrino cosmologies
  We use high-resolution hydrodynamical simulations run with the EAGLE model of
galaxy formation to study the differences between the properties of - and
subsequently the lensing signal from - subhaloes of massive elliptical galaxies
at redshift 0.2, in Cold and Sterile Neutrino (SN) Dark matter models. We focus
on the two 7 keV SN models that bracket the range of matter power spectra
compatible with resonantly-produced SN as the source of the observed 3.5 keV
line. We derive an accurate parametrisation for the subhalo mass function in
these two SN models relative to CDM, as well as the subhalo spatial
distribution, density profile, and projected number density and the dark matter
fraction in subhaloes. We create mock lensing maps from the simulated haloes to
study the differences in the lensing signal in the framework of subhalo
detection. We find that subhalo convergence is well described by a log-normal
distribution and that signal of subhaloes in the power spectrum is lower in SN
models with respect to CDM, at a level of 10 to 80 per cent, depending on the
scale. However, the scatter between different projections is large and might
make the use of power-spectrum studies on the typical scales of current lensing
images very difficult. Moreover, in the framework of individual detections
through gravitational imaging a sample of ~30 lenses with an average
sensitivity of M_sub=5x10^7M_sun would be required to discriminate between CDM
and the considered sterile neutrino models.
