A three-year record of the branch behaviour of the Z source GX 5-1 (4U 1758-25).
Abstract
A three-year random sample of the X-ray flux variations of the bright Galactic Bulge source GX 5-1 obtained with the Ginga All-Sky Monitor is presented. The data allow, for the first time, a statistical study of the branch behavior of a Z source. They cover 98 percent of the branch pattern displayed by the source (90 percent confidence). The pattern remained remarkably stable over the three years of observation. The horizontal branch (HB) extends over a factor of two in X-ray intensity, the source spends about equal time in the HB and in the normal branch (NB), and no flaring branch is detected. The branch behavior is random and uncorrelated on time-scales longer than several days. Consequences of these results for near-critical accretion rate models of the NB, and for the magnetic field strength of GX 5-1 relative to other Z sources are discussed.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- February 1991
- DOI:
- 10.1093/mnras/248.4.751
- Bibcode:
- 1991MNRAS.248..751V
- Keywords:
-
- Galactic Bulge;
- Neutron Stars;
- X Ray Binaries;
- Horizontal Branch Stars;
- Stellar Luminosity;
- Stellar Magnetic Fields;
- Stellar Mass Accretion;
- Stellar Models;
- Astrophysics