Measuring Galaxy Cluster Substructure with Flexion (Note: Special day!)

Benjamin Cain will be visiting and giving a special summer edition of Galaxy Lunch - note that he'll be speaking on a Thursday instead of the usual Friday!

Abstract: The abundance and masses of galaxy cluster substructures provide an important test of both dark matter properties and the details of cosmological structure formation models.  Gravitational lensing measurements of cluster mass distributions are an extremely useful tool both for measuring these substructures and for using clusters as “cosmic telescopes” to magnify the high-redshift universe.  I will present a method for improving the sensitivity and spatial resolution of galaxy cluster mass maps constructed from gravitational lensing data by including flexion, the gradient of lensing shear and convergence, as an additional constraint on the lensing potential.  This enables significant, otherwise undetectable, substructures to be found, and their masses accurately measured.