Long-term quasi-periodicity of 4U 1636-536 resulting from accretion disc instability
Abstract
We present the results of a study of the neutron star 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 collected until 2017.We have confirmed the previously discovered quasi-periodicity of 45 d present during 2004, and we have found it continued to 2006. At other epochs, the quasi-periodicity is only transient, and the quasi-period, if present, drifts from 32 to 72 days. We have applied a time-dependent accretion disc model to the interval with the significant X-ray quasi-periodicity. Although 4U 1636-536 is persistent, the observed quasi-periodicity can be well modelled by the hydrogen thermal-ionization instability occurring in outer regions of the accretion disc. For our best model, the period and the amplitude of the theoretical light curve agree well with those observed.
- Publication:
-
42nd COSPAR Scientific Assembly
- Pub Date:
- July 2018
- Bibcode:
- 2018cosp...42E3678W