Astronomy Colloquium

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Black Hole
October 4, 2018
4:00PM - 5:00PM
Location
1005 Smith Lab

Date Range
Add to Calendar 2018-10-04 16:00:00 2018-10-04 17:00:00 Astronomy Colloquium

What's in the Wind? Spectral Synthesis Modeling of Broad Absorption Line Quasars

Karen Leighly - University of Oklahoma

A significant fraction of quasars exhibit blueshifted broad absorption lines (BALs) in their rest-UV spectra, indicating powerful outflows emerging from the central engine. Despite years of study, the physical conditions of the outflowing gas are poorly understood.  Our group has developed SimBAL, a novel spectral synthesis fitting method for BAL quasars that uses Bayesian model calibration to compare synthetic to observed spectra. I will describe the construction of SimBAL, and illustrate its unique strengths by discussing the results from several projects.  The analysis of a HST spectrum of the low redshift broad absorption line quasar SDSS J0850+4544 reveals considerable structure as a function of velocity across the trough, including a high column density feature and a decrease in covering fraction with outflow velocity.  Analysis of a sample of FeLoBALs finds a four dex range of distance from the central engine.  Implications for the contribution of BALQSOs to black hole - galaxy feedback and future prospects will be briefly discussed.

 

1005 Smith Lab Department of Astronomy astronomy@osu.edu America/New_York public
Description

What's in the Wind? Spectral Synthesis Modeling of Broad Absorption Line Quasars

Karen Leighly - University of Oklahoma

A significant fraction of quasars exhibit blueshifted broad absorption lines (BALs) in their rest-UV spectra, indicating powerful outflows emerging from the central engine. Despite years of study, the physical conditions of the outflowing gas are poorly understood.  Our group has developed SimBAL, a novel spectral synthesis fitting method for BAL quasars that uses Bayesian model calibration to compare synthetic to observed spectra. I will describe the construction of SimBAL, and illustrate its unique strengths by discussing the results from several projects.  The analysis of a HST spectrum of the low redshift broad absorption line quasar SDSS J0850+4544 reveals considerable structure as a function of velocity across the trough, including a high column density feature and a decrease in covering fraction with outflow velocity.  Analysis of a sample of FeLoBALs finds a four dex range of distance from the central engine.  Implications for the contribution of BALQSOs to black hole - galaxy feedback and future prospects will be briefly discussed.