Constraints on Quasar Outflows

The spectra of quasars provide us with a wealth of insight into gas physics
under a wide range of different conditions. In particular, about 15% of quasars
show broad UV absorption from ionized winds outflowing at velocities up to 20%
of lightspeed, with mass loss rates comparable to the accretion rates required
to power quasars (possibly contributing significant feedback to galaxies during
their formation).  I will discuss some general trends seen among such `broad
absorption line' (BAL) quasars in the Sloan Digital Sky Survey, as well as a
recent detailed study of one particular quasar. This quasar has two overlapping
absorption systems whose profiles tell us that at least one of the systems
must consist of individual subunits rather than being a single structure.
Simple geometric probability arguments can then be used to constrain the
typical size of these subunits, whether they be spherical clouds or
linear filaments.


--
Prof. Patrick Hall