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|Title:||The Island State of the Atoll Source 4U 1820-30|
Van der Klis, M.
Jonker, P. G.
|Keywords:||Estels binaris de raigs X|
Estels de neutrons
Astronomia de raigs X
|Publisher:||Institute of Physics (IOP)|
|Abstract:||We study the rapid X-ray time variability in all public data available from the Rossi X-Ray Timing Explorer Proportional Counter Array on the atoll source 4U 1820-30 in the low-luminosity island state. A total of ~46 ks of data were used. We compare the frequencies of the variability components of 4U 1820-30 with those in other atoll sources. These frequencies were previously found to follow a universal scheme of correlations. We find that 4U 1820-30 shows correlations that are shifted by factors of 1.13 ± 0.01 and 1.21 ± 0.02 with respect to those in other atoll sources. These shifts are similar to, but smaller than, the shift factor of ~1.45 previously reported for some accreting millisecond pulsars. Therefore, 4U 1820-30 is the first atoll source that shows no significant pulsations but has a significant shift in the frequency correlations compared with the other three nonpulsating atoll sources.|
|Note:||Reproducció del document publicat a: http://dx.doi.org/10.1086/447761|
|It is part of:||Astrophysical Journal, 2005, vol. 633, num. 1, p. 358-366|
|Appears in Collections:||Articles publicats en revistes (Física Quàntica i Astrofísica)|
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