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تسجيل مستخدم جديدIs there a highly magnetized neutron star in GX 301-2?
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We present the results of an in-depth study of the long-period X-ray pulsar GX 301-2. Using archival data of INTEGRAL, RXTE ASM, and CGRO BATSE, we study the spectral and timing properties of the source. Comparison of our timing results with previously published work reveals a secular decay of the orbital period at a rate of simeq -3.25 times 10^{-5} d yr^{-1}, which is an order of magnitude faster than for other known systems. We argue that this is probably result either of the apsidal motion or of gravitational coupling of the matter lost by the optical companion with the neutron star, although current observations do not allow us to distinguish between those possibilities. We also propose a model to explain the observed long pulse period. We find that a very strong magnetic field B sim 10^{14} G can explain the observed pulse period in the framework of existing models for torques affecting the neutron star. We show that the apparent contradiction with the magnetic field strength B_{CRSF} sim 4 times 10^{12} G derived from the observed cyclotron line position may be resolved if the line formation region resides in a tall accretion column of height sim 2.5 - 3 R_{NS}. The color temperature measured from the spectrum suggests that such a column may indeed be present, and our estimates show that its height is sufficient to explain the observed cyclotron line position.
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We present two observations of the high-mass X-ray binary GX 301-2 with NuSTAR, taken at different orbital phases and different luminosities. We find that the continuum is well described by typical phenomenological models, like a very strongly absorb
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We report on the detection of a pulsating Fe Ka line in the High Mass X-ray Binary (HMXB) GX 301-2, from a 40-ks Chandra observation near periastron. The pulsations in the Fe Ka emission appeared only in the first 7 ks of the observation, with a peri
od and phase profile similar to those of the continuum. The presence of pulsed fluorescent lines is an unusual property in HMXBs. After 7 ks, the continuum flux increased by a factor of three, the Fe Ka flux increased only by about 10%, and the pulsating signal in the line disappeared. Finally, in the second half of the observation, both the continuum and the line flux dropped by a similar factor of 2. We suggest that the pulsating component of the Fe Ka line is coming from a transient non-isotropic distribution of dense gas around the neutron star, for example an accretion stream induced by periastron passage, or from the illuminated surface of the donor star.
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