Correlations between QPO frequencies and spectral parameters of GRS 1915+105 using AstroSat observations
Abstract
In this work, we study the correlation between quasi-periodic oscillation (QPO) frequency and the spectral parameters during various X-ray states in the black hole binary GRS 1915+105 which matches well with the predicted relativistic dynamic frequency (i.e. the inverse of the sound crossing time) at the truncated radii. We have used broad-band data of Large Area X-ray Proportional Counter and Soft X-ray Telescope instruments onboard AstroSat. Spectral fitting shows that the accretion rate varies from ~0.1 to ~5.0 × 1018 gm s-1 and the truncated radius changing from the last stable orbit of an almost maximally spinning black hole, ~1.2 to ~19 gravitational radii. For this wide range, the frequencies of the C-type QPO (2-6 Hz) follow the trend predicted by the relativistic dynamical frequency model and interestingly, the high-frequency QPO at ~70 Hz also follows the same trend, suggesting they originate from the innermost stable circular orbit with the same mechanism as the more commonly observed C-type QPO. While the qualitative trend is as predicted, there are quantitative deviations between the data and the theory, and the possible reasons for these deviations are discussed.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- September 2023
- DOI:
- 10.1093/mnras/stad2075
- arXiv:
- arXiv:2307.04622
- Bibcode:
- 2023MNRAS.524.2721D
- Keywords:
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- accretion;
- accretion discs;
- black hole physics;
- relativistic processes;
- X-rays: binaries;
- X-rays: individual: GRS 1915+105;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- doi:10.1093/mnras/stad2075