Microlensing of a Biconical Broad‐Line Region

The influence of microlensing in the profiles of the emission lines generatedin a biconical geometry is discussed. Microlensing amplification in thisanisotropic model is not directly related to the bicone's intrinsic size butdepends on the orientation of the bicone axis and on the cone aperture. Theorientation of the projected bicone with respect to the shear of themagnification pattern can induce very interesting effects, like thequasi-periodic enhancements of the red/blue part of the emission line profileor the lack of correlation between the broad line region (BLR) and continuumlight curves of QSOs. The emission line profiles of a BLR moving in a highcaustic concentration exhibit sharp features that are well defined inwavelength. These features (spikes) correspond to the scanning of thekinematics of the BLR by the caustic clusters. The biconical model canqualitatively reproduce with a transversal (with respect to the shear) movementof the BLR, the recurrent blue-wing enhancement detected in the emission lineprofile of the A image of the quasar lensed system SDSS J1004+4112. Theprobability of observing this repetitive event is almost a 2% for a fraction ofmatter in stars of a 5%. This result would make plausible the detection of thespectral variability in SDSS J1004+4112 under the hypothesis of microlensing ofa bicone.Comment: 21 figures, quality severely reduced. ApJ accepte