Abstract
We used two XMM-Newton and six Neutron Star Interior Composition
Explorer observations to investigate the fractional rms amplitude of the
millihertz quasiperiodic oscillations (mHz QPOs) in the neutron-star
low-mass X-ray binary 4U 1636-53. We studied, for the first time, the
fractional rms amplitude of the mHz QPOs versus energy in 4U 1636-53
down to 0.2 keV. We find that, as the energy increases from ∼0.2 to
∼3 keV, the rms amplitude of the mHz QPOs increases, different from
the decreasing trend that has been previously observed above 3 keV. This
finding has not yet been predicted by any current theoretical model;
however, it provides an important observational feature to speculate
whether a newly discovered mHz oscillation originates from the
marginally stable nuclear burning process on the neutron-star surface.
Original language | English |
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Article number | 120 |
Number of pages | 6 |
Journal | The Astrophysical Journal |
Volume | 895 |
Issue number | 2 |
DOIs | |
Publication status | Published - 3-Jun-2020 |
Keywords
- Low-mass x-ray binary stars
- Neutron stars
- Astrophysical explosive burning
- FREQUENCY
- BURSTS
- DISCOVERY
- QPOS
- LINE