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D.J. Norman (Univ. of Washington)
It has been proposed that gravitational lensing by large-scale structure can lead to an observed correlation of moderate redshift quasars (z ~0.7-2.0) and foreground galaxies (z ~0.2-0.3) through the phenomenon of magnification bias.
Results of a search for the signature of magnification bias in a survey of fields around 90 radio-bright (S5GHz > 1 Jy) quasars are presented. We have detected a 2 sigma correlation of these quasars and surrounding galaxies over a scale of 5 arcmin. We demonstrate that this correlation is likely the result of magnification bias and is unlikely to be caused by dust obscuration.
The observed correlation is inconsistent with gravitational lensing by Abell richness class = 1 clusters. However, the amplitude and scale of the observed correlation is consistent with recent semi-analytical models of quasar-galaxy correlations due to gravitational lensing by large-scale structure. These models incorporate non-linear evolution of the matter power spectrum.
The author would like to acknowledge support from NASA GSRP S96-UMF-003 and the Danforth-Compton Fellowship.