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S. Piraino (IFCAI/CNR), P. Kaaret (SAO), A. Santangelo (IFCAI/CNR), E. C. Ford (Amsterdam)
Quasi-periodic oscillations (QPOs) at frequencies near 1000 Hz in the x-ray emission from neutron star x-ray binaries are likely associated with orbital motion at the accretion disk inner edge and, thus, provide information on the behavior of the disk in the strong gravitational field near the neutron star. The behavior of the QPOs in certain systems has been interpreted as evidence for the existance of the marginally stable orbit, a key prediction of strong field general relativity. Here, we report on simultaneous high frequency x-ray timing and broad-band x-ray spectral observations of 4U 1820-30 made with RXTE and BeppoSAX and interpretation of the observations in the context of strong field gravity.
The author(s) of this abstract have provided an email address for comments about the abstract: pkaaret@cfa.harvard.edu