You can find the article from the Arxiv.

By simultaneously constraining the mass and radius of neutron stars, we are able to constraints the pressure-density relation of the cold dense matter. By using the cooling phase of X-ray bursts we can compare the changes in the observed spectra to the detailed model calculations to obtain these M and R measurements. One needs to be, however, careful, to only use the bursts that show signs of passive cooling as otherwise our delicate measurements might be contaminated.

After we obtain the mass-radius measurements we set up a Bayesian framework that enables us to set constraints also to the pressure-density relation inside neutron stars.