Luminosity dependent changes of pulse profiles in the X-ray binary GX 1+4

J. G. Greenhill, D. Galloway, M. C. Storey

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We have reviewed the X-ray pulse profiles from a large number of observations of the accreting binary pulsar GX 1+4 obtained during the last 25 years. The profiles cover various energy ranges between 1 and 100 keV. Using these data we present a coherent picture of present and past pulse profiles and the variations of these pulse profiles with time. The pulse shape is dependent on both the X-ray luminosity and whether the pulsar is spinning up or down. Profiles measured during the GX 1+4 high state in the 1970s are all trailing edge bright. Subsequently the profiles have generally been symmetric or leading edge bright. Rossi X-ray Timing Explorer (RXTE) satellite data taken in July 1996 show that similar pulse shape variations can occur on a timescale of hours. The implications of this new information for accretion models is discussed.

Original languageEnglish
Pages (from-to)254-258
Number of pages5
JournalPublications of the Astronomical Society of Australia
Issue number2
Publication statusPublished - 1 Jan 1998
Externally publishedYes


  • Accretion disks
  • Pulsars: individual: GX 1+4
  • X-rays: stars

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