Wenfei Yu, Shanghai Astron. Observ

Spectral States of X-Ray Binaries and Non-Stationary Accretion Onto Compact Stars

Much of our knowledge of accretion physics comes from observations of X-ray binaries. There exist distinct X-ray spectral states in black hole and neutron star X-ray binaries. These states have been interpreted or modeled as different regimes of mass accretion rates. However, recent X-ray observations performed with the RXTE and the Swift have shown solid evidence that these spectral states do not occur at fixed mass accretion rates, indicating mass accretion rate is not the only parameter in causing transitions between the spectral states as well as in determining the characteristic times scales in the accretion systems. In this talk, I will review the X-ray spectral and timing properties of Galactic X-ray binaries and show strong evidence that non-stationary accretion plays a dominate role during the spectral/timing state transitions in the bright X-ray binaries, which reveals non-stationary accretion regimes that are not well-understood. In the end, I will discuss opportunities to understand the accretion physics underneath the phenomena with current and future observations (such as with RXTE, Swift, LOFT and China's HXMT) .

Host:  Dong Lai