NOAO > Observing Info > Approved Programs > 2011A-0289
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NOAO > Observing Info > Approved Programs > 2011A-0289 |
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PI: Sarah Gallagher, University of Western Ontario, sgalla4@uwo.ca
Address: Department of Astronomy, London, Ontario, N6A 3K7, Canada
CoI: Karen Leighly, University of Oklahoma
CoI: Matthias Dietrich, Ohio State University
CoI: Sara Barber, University of Oklahoma
Title: Probing Quasar Outflows with GNIRS HeI* Spectroscopy
Abstract:
As a direct consequence of the luminosity generated through accretion,
quasars can eject energetic outflows at high velocities. These outflows are
directly observed in Broad Absorption Line (BAL) quasars through their deep,
blue-shifted absorption lines. To date, one of the main challenges in
constraining the fundamental properties (covering fractions and column
densities) of these outflows has been that these lines are typically heavily
saturated, but non-black (because of partial covering of the continuum).
However, we have recently demonstrated that HeI* observations at rest-frame
10830 and 3888 Angstroms are a particularly powerful means of circumventing
this problem for the thickest outflows because of the relatively small
population of atoms in the metastable state. This means that even at very
large column densities, HeI* absorption lines are not saturated. We propose
to exploit this feature of atomic physics to constrain, for the first time,
the column density and covering fraction of a sample of 8 BAL quasars with 13
hours of GNIRS spectroscopy. These important observations are a crucial step
towards measuring a fundamental parameter -- the kinetic luminosity of a
quasar outflow -- required to investigate the accleration mechanism in quasar
winds and the magnitude of quasar feedback.
National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360
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NOAO > Observing Info > Approved Programs > 2011A-0289 |
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