Publication Date:
2015-09-24
Description:
We investigate the spectral and timing properties of the millihertz quasi-periodic oscillations (mHz QPOs) in neutron-star low-mass X-ray binary 4U 1636–53 using XMM-Newton and Rossi X-ray Timing Explorer ( RXTE ) observations. The mHz QPOs in the XMM-Newton / RXTE observations show significant frequency variation and disappear right before type I X-ray bursts. We find no significant correlation between the mHz QPO frequency and the temperature of the neutron-star surface, which is different from theoretical predictions. For the first time we observed the full lifetime of a mHz QPO lasting 19 ks. Besides, we also measure a frequency drift time-scale ~15 ks, we speculate that this is the cooling time-scale of a layer deeper than the burning depth, possibly heated by the previous burst. Moreover, the analysis of all X-ray bursts in this source shows that all type I X-ray bursts associated with the mHz QPOs are short, bright and energetic, suggesting a potential connection between mHz QPOs and He-rich X-ray bursts.
Print ISSN:
0035-8711
Electronic ISSN:
1365-2966
Topics:
Physics
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