2006-08-03

micro and millilensing

Today Chris Kochanek (OSU) and Paul Schechter (MIT) faced off over microlensing and substructure, but unfortunately, they resolved their differences over breakfast, so no sparks flew. Schechter gave a beautiful, pedagogical description of the effects of micro- and milli-lensing (ie, the perturbations to smooth lens models by substructure and clumps). Kochanek showed that he can fit the detailed microlensing light curves of real gravitational lenses by brute force: He actually creates billions of totally random microlensing histories, and finds the few that fit each lens; from these he infers the masses of the stars, the velocities of the stars, and the sizes of the quasar emission regions.

In the afternoon, the Hubble Constant group worked late getting ready it's presentation for tomorrow: We have a much better upper limit on the Hubble Constant than the HST Key Project

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