Gravitational lensing is the distortion of distant background galaxies by all the intervening mass (dark or light, but there’s a lot more dark than light) that is between us and the distant galaxies. By carefully measuring the distortion, it is possible to measure the mass that is responsible.

Current areas of interest include:

Weak lensing by filaments of the cosmic web
The image to the right shows the signature of dark matter-dominated filaments (in red) that connect the dark matter halos where galaxies live (white spots). Read more about this result here. Journal paper.

Galaxy-galaxy lensing
The lensing of distant galaxies by other galaxies. This allows the measurement of the masses of the dark matter halos that surround galaxies. Journal paper.

Satellite galaxy lensing and tidal stripping.
By applying the same technique to galaxies that are satellites within a larger dark matter halo (such as members of rich clusters), the tidal stripping of their dark matter halos can be measured. Journal paper.

I am participating in the following lensing projects or surveys:

Canada-France Imaging Survey (CFIS)

I am the lead scientist of the r-band component (deep imaging over 5000 square degrees of sky). The survey is underway and will run until 2023. 

Euclid Satellite Mission (2022)

The Euclid mission is a European-led satellite mission that will launch in 2020.

I am a member of the Weak Lensing Working Group.

CFHTLenS. This survey is now complete.