NOAO >   Observing Info >   Approved Programs >   2007B-0295

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Proposal Information for 2007B-0295


PI: Daniel Nestor, University of Cambridge, dbn@ast.cam.ac.uk
Address: Institute of Astronomy, Madingley Road, Cambridge CB3 0HA, UK

CoI: Sandhya Rao, University of Pittsburgh
CoI: David Turnshek, University of Pittsburgh

Title: The galaxies associated with Ultra-strong MgII absorbers

Abstract: We propose to obtain images of ~ 15 fields towards quasars exhibiting ``ultra-strong'' MgII absorption in their spectra at redshifts z \lesssim 0.8. Such systems by definition exhibit strong/saturated low-ion absorption over lower-limit velocity spreads of 300-650 km s^-1. By exploiting huge absorber catalogues from the Sloan Digital Sky Survey, we are only now able to study these rare systems. Such extreme kinematics in low-ion gas are difficult to reconcile with the galaxy-sightline properties known for weaker systems. It is thought that these systems may have important consequences for star formation, hierarchical galaxy formation, and the distribution of metals into the IGM. We have recently published the first images of ultra-strong MgII absorbers (obtained with WTTM) with interesting initial results. However, the sample of only 15 fields is yet prohibitively small to properly constrain the nature of the physical processes that lead to the extreme kinematics that define these systems. We obtained images of an additional 15 fields using OPTIC in 2007a. Two additional nights in 2007b and three in 2008a will be sufficient to obtain images of the remainder of the highest priority targets, selected by the combination of relatively low-z and the highest absorption strength, and provide a total sample size large enough for robust statistical investigations. Such a catalog will represent of full census of the strongest MgII absorbers known at low-z.


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