High Frequency QPOs in Neutron Stars and Black Holes: Probing Dense Matter and Strong Gravitational Fields
arXiv:0705.0030
Abstract
Quasi-periodic oscillations (QPOs) have been discovered in the X-ray emission of many neutron stars and black holes. The QPOs with frequencies greater than about 300 Hz are thought to be produced near the surfaces of neutron stars and the event horizons of black holes. I first summarize some of the most important properties of the QPOs seen in neutron star and black hole systems. I then review some of the models that have been proposed and compare them with observational data. Finally, I describe how these QPOs can be used to determine the properties of dense matter and strong gravitational fields.
30 pages, 8 figures, published in "From X-Ray Binaries to Gamma-ray Bursts", proceedings of a symposium held in memory of Jan van Paradijs 6-9 June 2001, eds. E.P.J. van den Heuvel, L. Kaper, E. Roi, & R.A.M.J. Wijers