Cosmology Seminar

Measuring the mass function of dark matter subhalos with ALMA observations of gravitationally lensed dusty galaxies 
The number of observed dwarf satellites of the Milky Way is about three orders of magnitude lower than what cold dark matter (CDM) simulations predict, an issue that is referred to as the "Missing Satellite Problem". In this talk, I will discuss how in strong lensing systems we can detect low-mass dark matter subhalos in the lens galaxies by measuring the gravitationally-induced distortions that subhalos induce in the lensed images of background sources. Measuring the abundance of dark matter subhalos with strong lensing allows us to determine their mass function and to compare it with the predictions of CDM and other dark matter models. I will present our first detection of a subhalo using ALMA data and show how we can place constraints on the abundance of subhalos down to ~2e7 M_{odot} with these observations. I will also give a brief overview of our ongoing observational campaign to place stronger constraints at lower masses.