Phase-resolved spectroscopy of low frequency quasi-periodic oscillations in GRS 1915+105

Understand

X-ray radiation from black hole binary (BHB) systems regularly displays quasi-periodic oscillations (QPOs).

• In principle, a number of suggested physical mechanisms can reproduce their power spectral properties, thus more powerful diagnostics which preserve phase are required to discern between different models.
• In this paper, we first find for two Rossi X-ray Timing Explorer (RXTE) observations of the BHB GRS 1915+105 that the QPO has a well defined average waveform.
• That is, the phase difference and amplitude ratios between the first two harmonics vary tightly around a well defined mean.