Home  

  Research  

  People  

  Publications  

  Calendar  

    Lensing Cosmography

Dark matter, by its very nature, can only be detected indirectly. An example is the gravitational deflection of light from distant sources, known as gravitational lensing. This provides a clean geometrical probe of the mass distribution in the cosmic web bearing a strong imprint of the global cosmology and, consequently, that of the dark energy.

Strong gravitational lenses, like optical lenses with astigmatism, produce multiple images. The number density and distribution of separations for split images are sensitive diagnostics of mass density on various spatial scales. Quasars are particularly useful in strong lensing studies due to their point-like appearance and emission-line spectra carrying distance information.

Most lenses are too weak to form multiple images and only distort the background galaxies. Images of source galaxies can still be stretched (shear) and magnified (convergence) -- this is weak lensing. Were the source properties exactly known, we could obtain information about the lens by measuring shear and convergence. In practice we rely on statistics of the lensed population. The weak lensing technique promises more powerful constraints on the dark Universe than any other currently used method. During this project we will investigate strong as well as weak lensing probes.

BAO Clusters Lensing Theory Visualization QMU Resources