# Determine expansion rate of universe from gravitational waves LIGO?

I heard on the TED Radio Hour that the LIGO team was able to make an independent measurement of the Hubble constant and the increasing expansion rate of the universe when they detected the gravitational waves coming from a neutron star collision. How does measuring those waves tell you about the expansion rate of the universe?

The original paper is by Abbott et al. (2017), who find a relatively weak constraint of $H_0 = 70.0^{+12}_{-8}$ km s$^{-1}$/Mpc, which