Access

Article

Nature 316, 225-230 (18 July 1985) | doi:10.1038/316225a0; Accepted 10 June 1985

Intensity-dependent quasi-periodic oscillations in the X-ray flux of GX5-1

M. van der Klis*, F. Jansen†, J. van Paradijs‡, W. H. G Lewinparallel, E. P. J. van den Heuvel‡, J. E. Trümper & M. Sztajno

  1. *Space Science Department of ESA, European Space Research and Technology Centre, Postbus 299, 2200 AG Noordwijk, The Netherlands
  2. †Laboratory for Space Research Leiden, Postbus 9504, 2300 RA Leiden, The Netherlands
  3. ‡Astronomical Institute 'Anton Pannekoek', University of Amsterdam, Roetersstraat 15, 1018 WB Amsterdam, The Netherlands
  4. parallelMassachusetts Institute of Technology, Center for Space Research and Department of Physics, Room 37-627, Cambridge, Massachusetts 02139, USA
  5. Max-Planck Institute for Extraterrestrial Physics, 8046 Garching (b. Munich), FRG
Top

The X-ray flux of the bright galactic bulge source GX5-1 shows intensity-dependent quasi-periodic oscillations between approx20 and approx40 Hz, appearing as a broad peak in the power spectrum whose centroid frequency, width and integrated excess power strongly depend on the source intensity. The strength and steepness of low-frequency noise present in the power spectra below 15 Hz also depend on the source intensity. No evidence is found for coherent X-ray pulsations between 0.5 and 2,000 Hz. We discuss possible mechanisms to explain these new phenomena.