Long-term quasi-periodicity of 4U 1636-536 resulting from accretion disc instability
Abstract
We present the results of a study of the low-mass X-ray binary 4U 1636-536. We have performed temporal analysis of all available RXTE/ASM, RXTE/PCA, Swift/BAT and MAXI data. We have confirmed the previously discovered quasi-periodicity of ∼45 d present during ∼2004, however we found it continued to 2006. At other epochs, the quasi-periodicity is only transient, and the quasi-period, if present, drifts. We have then applied a time-dependent accretion disc model to the interval with the significant X-ray quasi-periodicity. For our best model, the period and the amplitude of the theoretical light curve agree well with that observed. The modelled quasi-periodicity is due to the hydrogen thermal-ionization instability occurring in outer regions of the accretion disc. The model parameters are the average mass accretion rate (estimated from the light curves), and the accretion disc viscosity parameters, α_{cold} and α_{hot}, for the hot and cold phases, respectively. Our best model gives relatively low values of α_{cold} and α_{hot}.
- Publication:
-
41st COSPAR Scientific Assembly
- Pub Date:
- July 2016
- DOI:
- 10.48550/arXiv.1507.00349
- arXiv:
- arXiv:1507.00349
- Bibcode:
- 2016cosp...41E2065W
- Keywords:
-
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- Submited to Astronomy&