Dusty origin of the Broad Line Region in active galaxies
  The most characteristic property of active galaxies, including quasars, are
prominent broad emission lines. I will discuss an interesting possibility that
dust is responsible for this phenomenon. The dust is known to be present in
quasars in the form of a dusty/molecular torus which results in complexity of
the appearance of active galaxies. However, this dust is located further from
the black hole than the Broad Line Region. We propose that the dust is present
also closer in and it is actually responsible for formation of the broad
emission lines. The argument is based on determination of the temperature of
the disk atmosphere underlying the Broad Line Region: it is close to 1000 K,
independently from the black hole mass and accretion rate of the object. The
mechanism is simple and universal but leads to a considerable complexity of the
active nucleus surrounding. The understanding the formation of BLR opens a way
to use it reliably - in combination with reverberation measurement of its size
- as standard candles in cosmology.
