Principal Investigator: Karen Leighly
PI Institution: University of Oklahoma Norman Campus
Investigators
(xml)
Title: What's in the Wind? Determining the Properties of Outflowing Gas in Powerful Broad Absorption Line Quasars
Cycle: 25
Abstract
A significant fraction of quasars exhibits blueshifted broad
absorption lines (BALs) in their rest-UV spectra, indicating powerful
outflows emerging from the central engine. These outflows may remove
angular momentum to enable black hole growth, enrich the intergalactic
medium with metals, and trigger quenching of star formation in
galaxies. Despite years of study, the physical conditions of the
outflowing gas are poorly understood. The handful of objects that have
been subjected to detailed analysis are atypical and characterized by
relatively narrow lines where blending is unimportant. However,
investigating more powerful BAL quasars will give us better insight
into the types of outflows much more likely to impact galaxy
evolution.
SimBAL is a novel spectral synthesis fitting method for BAL quasars
that uses Bayesian model calibration to compare synthetic to observed
spectra. With the model inputs of ionization parameter, column
density, and covering fraction specified, the gas properties giving
rise to the BAL features can be determined. We propose to apply
SimBAL to archival spectra of a sample of 14 luminous BAL quasars to
characterize their bulk outflow properties as a function of velocity
for the first time. Our results will show the range of parameters
typical of powerful outflows, an essential step towards constraining
the physics behind quasar winds and thus their impact on their
environments.