ﻻ يوجد ملخص باللغة العربية
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 $sim88degree$ 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 $sim56degree$. We discuss our results for these models in this source and the possible primary source of the hard X-rays.
We used two XMM-Newton and six Neutron Star Interior Composition Explorer (NICER) observations to investigate the fractional rms amplitude of the millihertz quasi-periodic oscillations (mHz QPOs) in the neutron-star low-mass X-ray binary 4U 1636-53.
We report on a simultaneous NuSTAR and Swift observation of the neutron star low-mass X-ray binary 4U 1728-34. We identified and removed four Type I X-ray bursts during the observation in order to study the persistent emission. The continuum spectrum
(abridged) We studied the energy and frequency dependence of the Fourier time lags and intrinsic coherence of the kHz QPOs in the NS LMXBs 4U 1608-52 and 4U 1636-53 using RXTE data. In both sources we confirmed energy-dependent soft lags of 10-100 mu
We used six simultaneous XMM-Newton and Rossi X-ray Timing Explorer plus five Suzaku observations to study the continuum spectrum and the iron emission line in the neutron-star low-mass X-ray binary 4U 1636-53. We modelled the spectra with two therma
We report the onset of a large amplitude, statistically significant periodicity (~46 d) in the RXTE/ASM data of the prototype X-ray burster 4U 1636-53, the X-ray flux of which has been gradually declining over the last four years. This behaviour is r