A Physical Model for Active Galactic Nuclei with Double‐peaked Broad Emission Lines

The double-peaked broad emission lines are usually thought to be linked toaccretion disks, however, the local viscous heating in the line-emitting diskportion is usually insufficient for the observed double-peaked broad-lineluminosity 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 diskcan photo-ionize the line-emitting disk portion, because the solid angle of theouter disk portion subtended to the inner region of the RIAF is too small. Wepropose that only those AGNs with sufficient matter above the disk (slowlymoving jets or outflows) can scatter enough photons radiated from the innerdisk region to the outer line-emitting disk portion. Our model predicts apower-law r-dependent line emissivity with an index ~2.5, which is consistentwith \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 theouter disk regions can be efficiently illuminated by the photons scattered fromthe electron-positron jets with \gamma_j<2. It is consistent with the fact thatno double-peaked emission line is present in strong radio quasars withrelativistic jets. For radio-quiet counterparts, slow outflows with Thomsonscattering depth ~0.2 can scatter sufficient photons to the line-emittingregions. This model can therefore solve the energy budget problem fordouble-peaked line emitters.Comment: 7 pages, accepted for publication in Ap