Article

Luminosity Dependent Changes of Pulse Profiles in the X-ray Binary GX 1+4

J. GreenhillPhysics Department, University of Tasmania, GPO Box 252C, Hobart, Tas. 7001, Australia;D. K. GallowayPhysics Department, University of Tasmania, GPO Box 252C, Hobart, Tas. 7001, Australia;Michelle C. StoreySpecial Research Centre for Theoretical Astrophysics, School of Physics, University of Sydney, NSW 2006, Australia;

Publications of the Astronomical Society of Australiajournal1998en

ABI

Abstract

Abstract 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.

Topics

Astrophysical Phenomena and Observations High-pressure geophysics and materials Pulsars and Gravitational Waves Research

Identifiers

DOI: 10.1071/as98254

Citations and references

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