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Session 36 - New Insights on X-ray Binaries - I.
Oral session, Wednesday, June 11
North Main Hall C/D,

[36.04] Sonic-Point Model for Kilohertz Brightness Oscillations in LMXBs

M. C. Miller (U. Chicago), F. K. Lamb, D. Psaltis (UIUC)

The discovery of kilohertz quasi-periodic brightness oscillations in several neutron-star low-mass X-ray binaries has given us a remarkable new probe of accretion near neutron stars and, very probably, the properties of matter at high densities. I will describe the sonic-point model for these QPOs. This model explains naturally the most important features of the kilohertz QPOs observed in the atoll sources, including their frequencies, large amplitudes, and high coherence, the frequent appearance of a pair of QPOs with similar FWHM, and the dependence of the QPO amplitude on photon energy. It is also consistent with the physical picture constructed previously from observations of the X-ray spectra and lower-frequency variability of weak-field accreting neutron stars in low-mass binary systems. I will discuss the constraints on the equation of state of dense matter that may be derived from high-frequency QPOs if the sonic-point interpretation is correct, and the prospects for future improvement of these constraints.

Program listing for Wednesday