Using Variability to Probe the Properties of Binary Orbit, Accretion Disk and Compact Object of Accreting Binaries

We propose to use variability to probe the properties of binary orbit, accretion disk and compact objectof accreting binaries. The time scales of variability of accreting binaries ranging from less than a millisecondto thousands of days can be periodic, quasi-period or even aperiodic. It allows us to probe different parts ofthe accreting binaries to learn the properties of these astrophysical systems. We plan to continue using theHilbert-Huang transform, which is a power tool for non-stationary oscillations and has been successfullyapplied some accreting systems to resolve their unstable periodicity variations, to analyze the superorbitalmodulations and quasi-periodic oscillations of X-ray binaries to reveal the natures of these phenomena. Onthe other hand, orbital period is the most fundamental physical parameter of an accreting binary. The orbitalperiod derivative can give us clue for the evolution of the binary system. In addition to the pointingobservations, orbital modulations of many X-ray binaries can be resolved by the light curves collected bywide-filed monitoring or sky scanning type of X-ray telescopes that allow us to continuously trace the orbitalperiod changes of these accreting binary systems. For an X-ray pulsar binary, not only the orbital period butalso the orbital and spin parameters can be precisely determined by using pulsar timing. With the refinedorbital and spin parameters, we are able to make pulsation phase-resolved spectra to study the emissionmechanics and physical parameters of neutron star, including the cyclotron resonance feature to directlymeasure the magnetic field of on the surface of neutron star.