"Clocked" Bursts From GS 1826-238
Abstract
We report on the long term monitoring of the GINGA transient source GS 1826-238 performed with the BeppoSAX Wide Fiels Camera (WFC) instrument, during four different observing campaigns covering October 1996 - September 1999. WFC detection of type-I bursting activity from the source ruled out its proposed black hole candidacy and clearly suggested the compact object related to GS 1826-238 to be a weakly magnetized neutron star. The analysis of the arrival times of the observed 78 bursts lead to the discovery of a recurrence of ~5.75 hours with a spread of 38 minutes (FWHM) along more than 3 years monitoring data (Ubertini et al., 1999). We performed a more detailed analysis of the whole available data, and evidence of shortening of the recurrence time, together with a drastic narrowing in the spread (down to a few minutes) was observed on a one year time scale. Possible relation with the source X-ray persistent emission is discussed.
Cite
@article{arxiv.astro-ph/0003331,
title = {"Clocked" Bursts From GS 1826-238},
author = {M. Cocchi and A. Bazzano and L. Natalucci and P. Ubertini and J. Heise and J. J. M. in 't Zand and J. M. Muller and M. J. S. Smith},
journal= {arXiv preprint arXiv:astro-ph/0003331},
year = {2009}
}
Comments
5 pages, 3 figures. Proc. of 5th Compton Symp., Portsmouth 1999