High Energy Physics Seminar
Halometry---mapping out the spectrum, location, and kinematics of nonluminous structures inside the Galactic halo---can be realized via effects that variable weak gravitational lensing induces on the proper motions of stars and other luminous background sources. Modern astrometric surveys provide unprecedented positional precision along with a leap in the number of cataloged objects. Astrometry thus offers a new and sensitive probe of collapsed dark matter structures over a wide mass range, from one millionth to several million solar masses. It opens up a window into the spectrum of primordial curvature fluctuations with comoving wavenumbers between 5 Mpc^−1 and 10^5 Mpc^−1, scales hitherto poorly constrained.
I will outline several detection strategies for dark matter substructure based on time-domain weak gravitational lensing. I will present preliminary results from two on-going analyses based on Gaia's second data release. Finally, I will discuss complementarity with other detection techniques, the implications for models of dark matter, and give an outlook to the future.