The reflection spectrum of the low-mass X-ray binary 4U 1636-53

Abstract

We present 3-79 keV NuSTAR observations of the neutron star low-mass X-ray binary 4U 1636-53 in the soft, transitional and hard state. The spectra display a broad emission line at 5-10 keV. We applied several models to fit this line: A GAUSSIAN line, a relativistically broadened emission line model, KYRLINE, and two models including relativistically smeared and ionized reflection off the accretion disc with different coronal heights, RELXILL and RELXILLLP. All models fit the spectra well, however, the KYRLINE and RELXILL models yield an inclination of the accretion disc of $\sim 88°$ with respect to the line of sight, which is at odds with the fact that this source shows no dips or eclipses. The RELXILLLP model, on the other hand, gives a reasonable inclination of $\sim 56°$. We discuss our results for these models in this source and the possible primary source of the hard X-rays.

9 pages, 8 figures

References in corpus (8)

• The role of the reflection fraction in constraining black hole spin
• Relativistic iron emission lines in neutron star low-mass X-ray binaries as probes of neutron star radii
• The NuSTAR spectrum of Mrk 335: Extreme relativistic effects within 2 gravitational radii of the event horizon?
• X-ray time variability across the atoll source states of 4U 1636--53
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• RossiXTE monitoring of 4U 1636-53: I. Long-term evolution and kHz Quasi-Periodic Oscillations
• Relation between spectral changes and the presence of the lower kHz QPO in the neutron-star low-mass X-ray binary 4U 1636-53
• Broad iron emission line and kilohertz quasi-periodic oscillations in the neutron star system 4U 1636-53

Cited by in corpus (4)

• A public relativistic transfer function model for X-ray reverberation mapping of accreting black holes
• The Comptonising medium of the neutron star in 4U 1636-53 through its lower kilohertz Quasi-Periodic Oscillations
• Accretion disks and coronae in the X-ray flashlight
• Study of the X-ray properties of the neutron-star binary 4U 1728$-$34 from the soft to hard state