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J. H. Swank (NASA/GSFC), C. B. Markwardt (NASA/GSFC and UMD)
Biweekly X-ray observations of the Galactic Bulge with the Rossi X-Ray Timing Explorer Proportional Counter Array for 5 years have built up statistics for different kinds of source behavior for low-mass binaries with neutron stars. The relation between the characteristic behaviors is not known. A typical transient may rise fast and decay exponentially in brightness and repeat this cycle after short (1/2 yr) or long intervals (20 yr). But an X-ray source also may be steady for an extended period (years) before the disk can become quiescent. It fades in the same way as do the transients which immediately decay. These sources have been reported to be very cool in quiescence; either not substantially heated by outbursts, or cooled very quickly. There are 3 sources active in the galactic bulge region during the last 5 years which were long lasting transients which turned off and 1 which turned on during that time. We will compare their X-ray characteristics in outburst, and in so far as available with Chandra, in quiescence.
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Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.