Cosmic Cartography: Lensing, Streams, and Small-Scale Structure
Surveys like DES, KiDS, and HSC stitch together shape measurements of millions of galaxies. Their weak lensing maps test how clumpy matter is, probing dark matter’s behavior beyond galaxies. Breakthroughs here are statistical and subtle, but decisive—small error bars, careful calibration, and cross-checks that make bold claims trustworthy. Subscribe for our lensing primers.
Cosmic Cartography: Lensing, Streams, and Small-Scale Structure
Long, delicate streams such as GD-1 and Palomar 5 act like seismographs for the Milky Way’s dark halo. Gaps and wiggles can betray encounters with dark subhalos. With Gaia’s precise motions, stream archaeology is blossoming into a breakthrough tool that tests whether dark matter is cold, warm, or self-interacting.