Transitions of black hole transients to the low/hard state under the microscope

We characterized the evolution of spectral and temporal properties of several Galactic black hole transients observed between 1996–2001 using the data from well sampled PCA observations close to the transition to the low/hard state. We showed that the changes in temporal properties are much sharper than the changes in the spectral properties, and it is much easier to identify a state transition with the temporal properties. The ratio of the power‐law flux to the total flux in the 3–25 keV band increases close to the transition, and the power‐law flux shows a sharp increase along with the changes in temporal properties during the transitions. In this work we concentrate on the decay of two recent outbursts, from 4U 1543‐47, and H1743‐322 and discuss the state transitions by tracking their daily, and sometimes hourly evolution, and interpret results based on the expectations from our earlier observations.