Poster Presentation

The NuSTAR View of a QPO Evolution of GRS 1915+105

Liang Zhang (Beijing Normal University)

We report a timing analysis of the black hole binary GRS 1915+105 with the NuSTAR observation. A strong type-C QPO below 2 Hz appears in the power density spectrum during the whole observation, whose frequency is correlated with the 3-25 keV count rate. The QPO shows a sudden increase in frequency along with a flux increase and a spectral softening. We discuss the possible origin of the QPO and the reason that leads to the QPO frequency variation. It is suggested that the reflection component has little influence on QPO frequency and the increase in QPO frequency could be associated with the moving inward of the outer part disk.