A Systematic Analysis of the Phase Lags Associated with the Type-C Quasi-periodic Oscillation in GRS 1915+105 - Archive ouverte HAL Access content directly
Journal Articles Monthly Notices of the Royal Astronomical Society Year : 2020

A Systematic Analysis of the Phase Lags Associated with the Type-C Quasi-periodic Oscillation in GRS 1915+105

Liang Zhang
  • Function : Author
Mariano Méndez
  • Function : Author
Diego Altamirano
  • Function : Author
Jinlu Qu
  • Function : Author
Li Chen
  • Function : Author
Konstantinos Karpouzas
  • Function : Author
Tomaso M. Belloni
  • Function : Author
Qingcui Bu
  • Function : Author
Yue Huang
  • Function : Author
Xiang Ma
Lian Tao
  • Function : Author

Abstract

We present a systematic analysis of the phase lags associated with the type-C quasi-periodic oscillations (QPOs) in GRS 1915+105 using RXTE data. Our sample comprises 620 RXTE observations with type-C QPOs ranging from ∼0.4 to ∼6.3 Hz. Based on our analysis, we confirm that the QPO phase lags decrease with QPO frequency, and change sign from positive to negative at a QPO frequency of ∼2 Hz. In addition, we find that the slope of this relation is significantly different between QPOs below and above 2 Hz. The relation between the QPO lags and QPO rms can be well fitted with a broken line: as the QPO lags go from negative to positive, the QPO rms first increases, reaching its maximum at around zero lag, and then decreases. The phase-lag behaviour of the subharmonic of the QPO is similar to that of the QPO fundamental, where the subharmonic lags decrease with subharmonic frequency and change sign from positive to negative at a subharmonic frequency of ∼1 Hz; on the contrary, the second harmonic of the QPO shows a quite different phase-lag behaviour, where all the second harmonics show hard lags that remain more or less constant. For both the QPO and its (sub)harmonics, the slope of the lag–energy spectra shows a similar evolution with frequency as the average phase lags. This suggests that the lag–energy spectra drive the average phase lags. We discuss the possibility for the change in lag sign, and the physical origin of the QPO lags.

Dates and versions

hal-02527095 , version 1 (31-03-2020)

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Liang Zhang, Mariano Méndez, Diego Altamirano, Jinlu Qu, Li Chen, et al.. A Systematic Analysis of the Phase Lags Associated with the Type-C Quasi-periodic Oscillation in GRS 1915+105. Monthly Notices of the Royal Astronomical Society, 2020, 494 (1), pp.1375-1386. ⟨10.1093/mnras/staa797⟩. ⟨hal-02527095⟩
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