Observational appearance of rapidly rotating neutron stars. X-ray bursts, cooling tail method, and radius determination (Suleimanov et al)

Vol. 639
7. Stellar structure and evolution

Observational appearance of rapidly rotating neutron stars. X-ray bursts, cooling tail method, and radius determination

by V. F. Suleimanov, J. Poutanen, K. Werner, 2020, A&A, 639, A33

There are several ongoing efforts to measure the neutron star equation of state. Various methods have been suggested to measure the neutron star mass and radius, including the cooling tail during "type I bursts", which occur when sufficient accreting matter deposits onto the neutron star surface, thus igniting the thermonuclear explosions. A specific spectral pattern is predicted due to the cooling neutron star surface, which can predict the neutron star radius with good accuracy. In this work, Suleimanov and colleagues compute the emission pattern for a rapidly rotating oblate (i.e., non-spherical) neutron star. This effect turns out to be important and overestimated by 3–3.5 km the neutron star radius (~30%).