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J. H. Swank (NASA/GSFC), C. B. Markwardt (UMD and NASA/GSFC), T. E. Strohmayer (NASA/GSFC)
The Rossi X-ray Timing Explorer PCA scans of the Galactic bulge (galactic longitude ±11\deg) detected 8 recent transients with peak intensities of 10 to 400 mCrab. Some of the transient events have a fast rise and slow decay typical of accretion disk instabilities. It is common for these decays to be oscillatory, rather than steady, as if there are waves within the disk. There are also outbursts with symmetric light curves. In particular, the source in Terzan 2, which had a very decade long doubling which peaked near the beginning of 1997, in 2004 has had two 30 day brightenings by a factor of 5 only 100 days apart. During each of these a burst was observed in snapshot observations near the peak. The source SLX 1735-269, also a burster, though not in our observations, has had irregularly repeated occurrences of fast swings between close to zero and 2-4 times normal. Some examples, such as the increase, drop, and slow recovery of GS 1826-238 suggest a change in the accretion disk such as emptying and refilling or a peculiar alignment. Follow up observations have provided deeper information about these transient sources. Possible explanations for their behavior will be addressed.
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Bulletin of the American Astronomical Society, 36 #3
© 2004. The American Astronomical Soceity.