Measurements of the Dark Matter Mass, Temperature and Spin

We summarize several measurements of the dark matter temperature-to-mass ratio, or equivalently, of the comoving root-mean-square thermal velocity of warm dark matter particles $v_{h\text{rms}}\left(1\right)$ . The most reliable determination of this parameter comes from well measured rotation curves of dwarf galaxies by the LITTLE THINGS collaboration: $v_{h\text{rms}}\left(1\right)=406\pm 69\text{？}\text{m}/\text{s}$ . Complementary and consistent measurements are obtained from rotation curves of spiral galaxies measured by the SPARC collaboration, density runs of giant elliptical galaxies, galaxy ultra-violet luminosity distributions, galaxy stellar mass distributions, first galaxies, and reionization. Having measured $v_{h\text{rms}}\left(1\right)$ , we then embark on a journey to the past that leads to a consistent set of measured dark matter properties, including mass, temperature and spin.