Abstract
Quasi-periodic oscillations (QPOs) at frequencies near 1000 Hz were recently discovered in several X-ray binaries containing neutron stars. Two sources show no correlation between QPO frequency and source count rate. We suggest that the QPO frequency is determined by the Keplerian orbital frequency near the marginally stable orbit predicted by general relativity in strong gravitational fields. The radius of the marginally stable orbit does not depend on the luminosity or mass accretion rate of the source; therefore the QPO frequency does not depend on the source count rate. The QPO frequencies observed from 4U 1636-536 imply that the mass of the neutron star is 2.02 ± 0.12 M☉. Interpretation of the 4.1 keV absorption line observed from 4U 1636-536 as due to Fe XXV ions then implies a neutron star radius of 9.6 ± 0.6 km.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
