New Gravitational Lenses, Time Delays, and Microlensing with the Magellan Telescopes

Massachusetts Institute Of Technology, Cambridge MA

Investigators

Abstract

AST-0206010 Schechter, Paul L. In this project two distinct strategies will be used to search at optical wavelengths for gravitationally lensed quasars. First, conventional (but highly automated) pointed direct images will be obtained of 6500 known quasars with the Magellan I (Baade) telescope. Second, direct images in three filters will be obtained for 1000 square degrees with 0.24 arcsecond pixels and subarcsecond resolution with the MPIA 2.2-m telescope. A conservative estimate of the expected number of lenses is 32, exceeding the number of systems found separately in the past two decades by either optical or radio techniques. As 90% of quasars are radio quiet, these two searches will complement recent successful radio searches and furnish systems bright enough for extensive followup at optical wavelengths. Gravitationally lensed quasars select galaxies by mass, rather than light. Samples of lensing galaxies, typically at intermediate redshifts, complement intermediate redshift samples selected by apparent magnitude. They give mass functions rather than luminosity functions, an important component of galaxy evolution models. Lensed quasars also permit measurement of the Hubble constant, the cosmological parameter which sets the scale for the Universe. The Hubble constant is sufficiently important that it warrants a measurement completely independent of the traditional parallax and standard candle based methods. ***