Speaker
Description
In this talk, I will present recent constraints on the free-streaming DM particle mass from observations of quadruply lensed quasars. Characterizing the population of low-mass dark matter halos, both in terms of their abundances and concentrations allows us to connect to the underlying particle physics of dark matter. The magnifications of strongly lensed quasars provide a probe of the abundance of structure since the relative brightnesses of the images can be perturbed by low-mass halos both in the lens and along the line-of-sight. In this talk, I will present measurements of the relative magnifications of the strongly lensed warm dust emission in a sample of 9 systems measured with JWST MIRI multi-band imaging, which are used to constrain the half-mode mass of the halo mass function. This is the first science result for the JWST GO-2046 program, which will continue for the full 31 lenses. I constrain a WDM model and find an upper limit on the half-mode mass of $10^{7.6} M_\odot$ at posterior odds of 10:1. This corresponds to a lower limit on a thermally produced dark matter particle mass of 6.1 keV. This is the strongest gravitational lensing constraint to date, and comparable to those from independent probes such as the Ly$\alpha$ forest and Milky Way satellite galaxies.
