  It has been claimed that the variability of field quasars resembles
gravitational lensing by a large cosmological population of free-floating
planets with mass of about 10 Earths. But Galactic photometric monitoring
experiments, on the other hand, exclude a large population of such
planetary-mass gravitational lenses. These apparently contradictory pieces of
evidence can be reconciled if the objects under consideration have a mean
column-density that lies between the critical column-densities for
gravitational lensing in these two contexts. Dark matter in that form is known
to be weakly collisional, so that a core develops in galaxy halo density
profiles, and a preferred model has already been established. Here we consider
what such a model implies for Q2237+0305, which is the best-studied example of
a quasar that is strongly lensed by an intervening galaxy. We construct
microlensing magnification maps appropriate to the four macro-images of the
quasar -- all of which are seen through the bulge of the galaxy. Each of these
maps exhibits a caustic network arising from the stars, plus many small,
isolated caustics arising from the free-floating "planets" in the lens galaxy.
The "planets" have little influence on the magnification histograms but a large
effect on the statistics of the magnification gradients. We compare our
predictions to the published OGLE photometry of Q2237+0305 and find that these
data are consistent with the presence of the hypothetical "planets". However,
the evidence is relatively weak because the OGLE dataset is not well suited to
testing our predictions and requires low-pass filtering for this application.
New data from a large, space-based telescope are desirable to address this
issue.

Cosmology and Nongalactic Astrophysics;Astrophysics of Galaxies