A STUDY IN WEAK LENSING MAGNIFICATION WITH WISE AGN AND SDSS GALAXIES

Abstract

A weak lensing measurement of the magnification bias with ~ 700,000 WISE AGN and ~ 6,600,000 SDSS galaxies from scales of \(\theta\) ~ .001\(^{\circ}\) to \(\theta\) ~ 1\(^{\circ}\) is presented. A positive signal is detected at scales smaller than a degree, probing physical scales of 30h\(^{-1}\)kpc - 7h\(^{-1}\)Mpc, with the median redshift of the galaxy lenses z ~ .175. By using WISE AGN as sources, higher surface densities are found, a largely unbiased population is chosen, and reddening systematics are negligible. Efforts are made to minimize physical clustering contamination, though the angular correlation function shows an excess on scales below \(\theta\) ~ .01\(^{\circ}\) that could be due to a 1-halo term or redshift contamination. Signal dilution by stars is not well constrained, but shown to be subdominant. An empirical model is fit to the observed angular correlation function, allowing the count slope to vary. That the fits indicate an amplitude that is proportional to the count slope merits further theoretical modeling, including a 1-halo term, which could explain the observed excess of signal on scales smaller than .01\(^{\circ}\).