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G. Becker, W. L. W. Sargent (CalTech), M. Rauch (OCIW)
Studies of the intergalactic medium along parallel lines of sight towards quasar pairs offer valuable information on the sizes of intervening absorbers as well as provide the basis for a test of the cosmological constant. We present a study of two high-redshift pairs with moderate separation observed with Keck ESI, Q1422+2309A/Q1424+2255 (z = 3.63, \theta = 39'') and Q1439-0034A/B (z = 4.25, \theta = 33''). The crosscorrelation of transmitted flux in the Ly\alpha forest shows a strong peak at zero velocity lag in both pairs, suggesting that the Ly\alpha absorbers are coherent over scales > 230-300 proper kpc. Two strong C IV systems at z = 3.4, closely separated along the line of sight, appear in Q1439B but not in Q1439A, consistent with the picture of outflowing material from an intervening galaxy. In contrast, a Mg II system at z = 1.68 does appear in both Q1439A and B. This suggests either a single absorber of size > 280 kpc or two separate, clustered absorbers. We additionally examine the impact of spectral characteristics on applying the Alcock-Paczynski test to quasar pairs, finding a strong dependence on resolution.
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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.