partly obscured accretion disk model to explain Shifted broad Balmer
  emission lines of Active Galactic Nuclei
  We present a new model to explain the appearance of red/blue-shifted broad
low-ionization emission lines, especially emission lines in optical band, which
is commonly considered as an indicator of radial motion of the line emitting
gas in broad emission line regions (BLRs) of Active Galactic Nuclei (AGN). We
show that partly obscured disk-like BLRs of dbp emitters (AGN with double-peak
broad low-ionization emission lines) can also successfully produce shifted
standard Gaussian broad balmer emission lines. Then we calculate two kinds of
BH masses for AGN with shifted broad balmer emission lines selected from SDSS.
We find that the BH masses calculated from M-sigma relation are systematically
larger than virial BH masses for the selected objects, even after the
correction of internal reddening effects in BLRs. The smaller virial BH masses
than BH masses from M-sigma relation for objects with shifted broad emission
lines are coincident with what we expect from the partly obscured accretion
disk model. Thus, we provide an optional better model to explain the appearance
of shifted broad emission lines, especially for those objects with
underestimated virial BH masses.
