AAO Colloquium.
Thursday, 20 June 2002- 3:30pm AAO Conference Room
Odd BALs from the Sloan Digital Sky Survey
Pat Hall
Princeton University
Pontifica Universidad Catolica de Chile
About 10% of quasars show Broad Absorption Line troughs from gas in outflows
with velocities of typically 0.1c. It is likely that all quasars have BAL
outflows, at least at some point in their lifetimes, and BAL mass loss rates
are comparable to the accretion rates required to power quasars. Thus an
understanding of BAL outflows is required to understand quasars as a whole.
The most unusual BAL quasars help us understand the full range of parameter
space spanned by BAL outflows. The Sloan Digital Sky Survey has confirmed
that populations of unusual BAL quasars exist. These include objects with
almost complete absorption below MgII, objects heavily reddened by dust with
an extinction curve even steeper than the SMC, possible transition objects
between low- and high-ionization BAL quasars, and objects with redshifted
absorption troughs (perhaps due to absorption of an extended continuum source
by a rotation-dominated disk wind). I will discuss these different
types of objects and what they tell us about BAL outflows.
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