AR 15035 (Archival Research)

Mon Jul 15 06:07:52 GMT 2024

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

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.