Compton processes in the bright AGN MCG+8-11-11
  We present preliminary results on the hard X-ray emission properties of the
Seyfert 1.5 galaxy MCG+8-11-11 as observed by INTEGRAL and SWIFT. All the
INTEGRAL IBIS/ISGRI data available up to October 2009 have been analyzed
together with two SWIFT/XRT snapshot observations performed in August and
October 2009, quasi-simultaneously to INTEGRAL pointed observations of
MCG+8-11-11. No correlation is observed between the hard X-ray flux and the
spectral slope, while the position of the high-energy cut-off is found to have
varied during the INTEGRAL observations. This points to a change in the
temperature of the Comptonising medium from a minimum value of kT = 30-50 keV
to values larger than 100-150 keV. There is no significant detection of Compton
reflection, with a 3 sigma upper limit of R < 0.2, and no line has been
detected at 112 keV, as previously claimed from HEAT observations (112 keV flux
F < 2.4e-4 ph/cm^2/s). The variability behaviour of MCG+8-11-11 is found to be
similar to that shown by IC 4329A, with different temperatures of the electron
plasma for similar flux levels of the source, while other bright Seyfert
galaxies present different variability patterns at hard X-rays, with spectral
changes correlated to flux variations (e.g. NGC 4151).
