Harvard University Department of Astronomy

The Cosmological Constant Gravitational Lensing Basic Idea: Change the volume of space back to a given time, changes odds that a foreground object (e.g. galaxy) will get close enough to line of sight of a background object to lens it. Gravitational lensing What it is strong, microlensing and weak lensing strong lensing by a point mass observed examples Use as measurement of Lambda Observations Method advantages: statistics improving, many lenses being discovered sources of error: extinction, unwanted dependence on galaxy properties, discovery process Current Results Castles survey, CLASS survey proposed projects Other cosmological tests lensing can be used for matter (not just luminous) profiles Hubble constant clumpy dark matter large scale structure -- to be discussed later Some References Home Syllabus References Lecture References Useful Links Contact Info