  The double-peaked broad emission lines are usually thought to be linked to
accretion disks, however, the local viscous heating in the line-emitting disk
portion is usually insufficient for the observed double-peaked broad-line
luminosity in most sources. Our calculations show that only a small fraction (<
2.3 per cent) of the radiation from the RIAF in the inner region of the disk
can photo-ionize the line-emitting disk portion, because the solid angle of the
outer disk portion subtended to the inner region of the RIAF is too small. We
propose that only those AGNs with sufficient matter above the disk (slowly
moving jets or outflows) can scatter enough photons radiated from the inner
disk region to the outer line-emitting disk portion. Our model predicts a
power-law r-dependent line emissivity with an index ~2.5, which is consistent
with \beta~2-3 required by the model fittings for double-peaked line profiles.
Using a sample of radio-loud double-peaked line emitters, we show that the
outer disk regions can be efficiently illuminated by the photons scattered from
the electron-positron jets with \gamma_j<2. It is consistent with the fact that
no double-peaked emission line is present in strong radio quasars with
relativistic jets. For radio-quiet counterparts, slow outflows with Thomson
scattering depth ~0.2 can scatter sufficient photons to the line-emitting
regions. This model can therefore solve the energy budget problem for
double-peaked line emitters.
