Narrowing down neutron stars' crustal properties using cooling data*

LMXBs KS 1730-260 and MXB 1659-29 are two neutron stars among many that have been observed to accrete matter from a companion star and cool after quiescence begins. Cooling data for KS 1730-260 and MXB 1659-29 have been provided by the Chandra and XMM-Newton telescopes. Using Dr. Ed Brown’s dStar we ran models for stars with solar masses of 1.2 Msun to 1.8 Msun to check if a relationship between the inferred crustal impurity of these stars and the slope of their symmetry energies existed. The most accurate models for each mass group (1.2, 1.4, 1.6, and 1.8 Msun) had symmetry energies with slopes of L=20. The higher mass stars (1.6, 1.8 Msun) also had slopes of L=40 in their most accurate results. The value of the impurity parameter for each mass group increased as M increased: for M=1.2 Msun, Qimp varied between 0.01-0.092. For M=1.8 Msun, Qimp varied between 0.38-3.38.