Geometry and kinematics of the broad emission line region in the lensed
  quasar Q2237+0305
  Line profile distortions are commonly observed in gravitationally lensed
quasar spectra. These distortions are caused by microlensing from the stars in
the lensing galaxy, which produce differential magnification of spatially and
kinematically separated parts of the broad line region (BLR). The
quasi-simultaneous visible and near-infrared spectroscopy of the lensed quasar
Q2237+0305 reveals strong microlensing-induced line deformations in the
high-ionization CIV $\lambda$ 1549 \AA and the low-ionization H$\alpha$
emission lines. We use this effect to constrain the BLR size, geometry, and
kinematics in Q2237+0305. For this purpose, we modeled the deformation of the
emission lines for three representative BLR models: a Keplerian disk, an
equatorial wind, and a biconical polar wind. We considered various inclinations
with respect to the line of sight. We find that the observed microlensing
effect, characterized by a set of four indices, can only be reproduced by a
subsample of the considered BLR models. The microlensing analysis favors a
Keplerian disk model for the regions emitting the CIV and the H$\alpha$
emission lines. A polar wind model remains possible for the CIV BLR, although
it is less likely. The equatorial wind model is totally excluded. A preferred
inclination of the BLR of 40$\deg$ is found, in agreement with expectations for
a type 1 AGN and past constraints on the accretion disk inclination. The
half-light radius of the BLR is $ r_{\rm 1/2} \simeq$ 47$\pm$19 light-days,
with no significant difference between the CIV and H$\alpha$ BLRs. The size of
the CIV BLR agrees with the radius-luminosity relation derived from
reverberation mapping, while the size of the Balmer line BLR is one order of
magnitude smaller, possibly revealing different quasar properties at high
luminosities and high accretion rates.
