Peeking into a Neutron Star: Neutrons, Condensates, or Quarks?
Univ. of Arizona
Determining the masses and radii of neutron stars has been hampered for decades by a number of model uncertainties as well as by the lack of accurate measurements of different spectroscopic phenomena from a single source that would break the degeneracies between the neutron star parameters of interest. I discuss how we can now overcome these problems by combining recent developments in our understanding of neutron star atmospheres with observations of distinct phenomena from the same neutron star source. In particular, I report the first unique measurement of the mass and radius of the neutron star in EXO 0748-676. The high inferred mass and large radius of this neutron star rule out all the soft equations of state of neutron star matter. This result shows that condensates and unconfined quarks do not appear under the conditions found in the centers of the neutron stars.