A comparative analysis of QPO frequencies and frequency relations in neutron star and black hole low mass X-ray binaries

In this thesis, entitled 'A comparative analysis of QPO frequencies and frequency relations in neutron star and black hole low mass X-ray binaries', we use complete data sets of a selection of neutron star (NS) and black hole (BH) low mass X-ray binaries (LMXBs) in the Rossi X-ray Timing Explorer archive to compare QPO-frequencies and frequency relations between sources to test QPO models that use relativistic effects, and to constrain the neutron star equation of state. Using a new, accurate method, we measure QPO frequency correlations in neutron star LMXBs with known spin and presumed low magnetic field strengths (Ch. 2), and in accreting millisecond pulsars with presumably stronger magnetic fields (Ch. 4). We apply this new method to low-frequency QPOs in BH LMXBs to investigate `harmonic' frequency ratios (Ch. 5). Additionally, we compare the highest kHz QPOs detected in NS LMXBs to predictions for the maximum orbital frequency around rotating neutron star models using realistic equations of state (Ch. 3).