There are many speculative scenarios about QCD matter in the regions of low temperature and high baryon density. Since it is hard to impose first-principles constraints there, any hints from experimental observations should be useful for us to understand what we know and what we still miss. In this talk, I will explain what we can learn from the neutron star observations. Recently, several groups (including us) reported that the equation of state along the high-density direction unexpectedly behaves in a different way from the high-temperature matter. The prospect of gravitational signals from binary neutron star mergers is mentioned in this regard with emphasis on our finding that there should be a mass window in the binary system that is particularly sensitive to QCD phase transition scenarios.
Zoom link: https://bnl.zoomgov.com/j/1605020278?pwd=cHJ1bDRuK1FDNnZLSnpxVkZhcDQ3QT09