Deep+Wide Lensing Surveys will Provide Exquisite Measurements of the Dark Matter Halos of Dwarf Galaxies

Abstract

The advent of new deep+wide photometric lensing surveys will open up the possibility of direct measurements of the dark matter halos of dwarf galaxies. The HSC wide survey will be the first with the statistical capability of measuring the lensing signal with high signal-to-noise at log(M*)=8. At this same mass scale, LSST will have the most overall constraining power with a predicted signal-to-noise for the galaxy-galaxy lensing signal around dwarfs of SN=200. WFIRST and LSST will have the greatest potential to push below the log(M*) = 7 mass scale thanks to the depth of their imaging data. Studies of the dark matter halos of dwarf galaxies at z=0.1 with gravitational lensing are soon within reach. However, further work will be required to develop optimized strategies for extracting dwarfs samples from these surveys, determining redshifts, and accurately measuring lensing on small radial scales. Dwarf lensing will be a new and powerful tool to constrain the halo masses and inner density slopes of dwarf galaxies and to distinguish between baryonic feedback and modified dark matter scenarios.