Using Velocity Fields to Improve Gravitational Lensing Mass Measurements of Galaxies and Galaxy Clusters

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The mass content of galaxies and clusters of galaxies is difficult to measure if the matter is not emitting light. One way of measuring this mass is by looking at distortions in the shapes of more distant galaxies as their light is deflected by the gravitational influence of the mass in the galaxy or cluster of interest. This project will test to see if looking for distortions in the velocities of the stars in the distant galaxies can help improve these measurements. The project will use simulations to see what improvements can be made using the new technique.Current weak lensing surveys require large numbers of lensed galaxies to be averaged in order to beat down the noise in measurements of lensing mass. This project will look at the benefits of including measurements of the velocity field of the lensed galaxies. This should reduce the number of galaxies needed to obtain the same signal-to-noise, and therefore increase the angular resolution of the mass distributions that can be measured using weak lensing. The project will use cosmological simulations to assess the efficacy of this technique and identify ways to maximize the return on observational investment in weak lensing surveys.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.