AAS 207th Meeting, 8-12 January 2006
Session 120 Intergalactic Medium and Absorption Line Systems
Poster, Wednesday, 9:20am-6:30pm, January 11, 2006, Exhibit Hall

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[120.07] The Value of Increased Resolution for Study of Quasar Absorption Line Systems

A. Narayanan, T. Misawa, J. Charlton (Pennsylvania State University)

A revolution in our understanding of quasar absorption line systems resulted from the last dramatic increase in spectral resolution to R=45,000, a decade ago with the HIRES spectrograph on Keck I. Detection limits decreased dramatically and the absorption profiles for systems produced by galaxies and by the intergalactic medium were resolved into complex kinematic structures. With the advent of 30-meter class telescopes, the possibility for a similar revolution is upon us. Following Tappe and Black (2001), who presented an R=100,000 spectrum obtained with UVES on VLT, we are beginning to evaluate the potential of higher resolution observations of quasars. We obtained a R=120,000 spectrum of the bright quasar PG 1634+706 in a pilot program using the HDS on the Subaru Telescope. The two single-cloud, weak MgII absorbers at z=0.81 and z=0.90 along the line of sight appear to be resolved in this spectrum (while they were not resolved at R=45,000). The strong MgII absorber at z=0.99 is separated into more components, which will allow us to refine models of the physical conditions in the galaxy that produces it. In the multiple cloud, weak MgII absorber at z=1.04 it was possible to detect a weak MgII component, that was not previously known. Finally, the Milky Way Galaxy absorption has extremely narrow components (Doppler b parameters < 1 km/s), which are probably not even resolved at R=120,000. The existence of such narrow components and the increased sensitivity to weak lines, suggests that the next boost in resolution will indeed enhance studies of quasar absorption line systems.

This work was supported by the National Science Foundation under grant AST 04-07138 and by NASA through grant NAG5-6399 NNG04GE73G.

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