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The startling discovery of Prochter et al. (2006) that the frequency of verystrong (W_r(2796)>1 A) MgII absorbers along gamma-ray burst (GRB) lines ofsight ([dN/dz]_{GRB} = 0.90) is more than three times the frequency alongquasar lines of sight ([dN/dz]_{QSO} = 0.24), over similar redshift ranges, hasyet to be understood. We reconsider the possibility that the excess of verystrong MgII absorbers toward GRBs is intrinsic either to the GRBs themselves orto their immediate environment, and associated with bulk outflows withvelocities as large as v_{max} ~ 0.3c. In order to examine this hypothesis, weaccumulate a sample of 27 W_r(2796) > 1 A absorption systems found toward 81quasars, and compare their properties to those of 9 W_r(2796)>1 A absorptionsystems found toward 6 GRBs; all systems have been observed at high spectralresolution (R = 45,000) using the Ultraviolet and Visual Echelle Spectrographon the Very Large Telescope. We make multiple comparisons of the absorberproperties across the two populations, testing for differences in metallicity,ionization state, abundance patterns, dust abundance, kinematics, and phasestructure. We find no significant differences between the two absorberpopulations using any of these metrics, implying that, if the excess absorberstoward GRB lines of sight are indeed intrinsic, they must be produced in aprocess which has strong similarities to the processes yielding strong MgIIsystems in association with intervening galaxies. Although this may seem apriori unlikely, given the high outflow velocities required for any intrinsicmodel, we note that the same conclusion was reached, recently, with respect tothe narrow absorption line systems seen in some quasars.

Testing the Possible Intrinsic Origin of the Excess of Very Strong MgII Absorbers Along GRB Lines-of-Sight