Discovery of a pulsating Fe Ka line in GX 301-2

Abstract

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 period 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.

8 pages, 5 figures, MNRAS accepted

Cited by in corpus (8)

• Observations of a GX 301-2 Apastron Flare with the X-Calibur Hard X-Ray Polarimeter Supported by NICER, the Swift XRT and BAT, and Fermi GBM
• The Symbiotic X-ray binaries Sct X-1, 4U 1700+24 and IGR J17329-2731
• Pulsating iron spectral features in the emission of X-ray pulsar V0332+53
• Timing and spectral variability of high mass X-ray pulsar GX 301--2 over orbital phases observed by Insight-HXMT
• X-ray reprocessing in accreting pulsar GX 301-2 observed with Insight-HXMT
• On the spin-up events and spin direction of the X-ray pulsar GX 301-2
• The spatial distribution of circumstellar material of the wind-fed system GX 301-2
• Monte-Carlo simulations on possible collimation effects of outflows to fan-beamed emission of ultraluminous accreting X-ray pulsars