Monday

EXO 0748-676 is a neutron star low-mass X-ray binary that exhibits sharp X-ray eclipses of 498-second duration every 3.82 hours. I will present results from our eclipse mapping analysis, which involves modelling the eclipse profile in several energy bands to place constraints on the binary mass ratio and inclination. Our results indicate a heavy neutron star, thus requiring a harder equation of state for neutron star matter. While eclipse mapping has the potential to place constraints on the radius of the compact object, this has not been possible for EXO 0748-676 due to an irradiated wind surrounding the low-mass companion, which we believe to be driven by the neutron star itself. Further study of the eclipse profile has uncovered characteristics typically associated with spider pulsars, including an asymmetric eclipse profile and a strong energy dependence in the eclipse start and end times. The neutron star in EXO 0748-676 has a millisecond spin frequency, known due to intermittent X-ray pulsations, but radio pulsations have, thus far, never been observed. We suggest that EXO 0748-676 could eventually become a radio pulsar, evolving first into a spider pulsar system followed by an isolated pulsar as the companion star is ablated further.