Size of the accretion disk in the gravitationally lensed quasar SDSS
  J1004+4112 from the statistics of microlensing magnifications
  We present eight monitoring seasons of the four brightest images of the
gravitational lens SDSS J1004+4112 observed between December 2003 and October
2010. Using measured time delays for the images A, B and C and the model
predicted time delay for image D we have removed the intrinsic quasar
variability, finding microlensing events of about 0.5 and 0.7 mag of amplitude
in the images C and D. From the statistics of microlensing amplitudes in images
A, C, and D, we have inferred the half-light radius (at {\lambda} rest = 2407
{\AA}) for the accretion disk using two different methods,
$R_{1/2}=8.7^{+18.5}_{-5.5} \sqrt{M/0.3 M_\odot}$ (histograms product) and
$R_{1/2} = 4.2^{+3.2}_{-2.2} \sqrt{M/0.3 M_\odot}$ light-days ($\chi^2$). The
results are in agreement within uncertainties with the size predicted from the
black hole mass in SDSS J1004+4112 using the thin disk theory.
