Chin-Ping Hu"A long-term X-ray monitoring of the ultraluminous X-ray source NGC 5408 X-1 with Swift reveals the presence of dips but no orbital period"
時間/地點： 2013-12-05 12:00 [S4-914]
摘要：
NGC 5408 X-1 is a well-studied ultraluminous X-ray source (ULX) that has been seen to emit in X-rays persistently above the Eddington limit of a stellar mass black hole for years. In this paper we report on the most extensive X-ray monitoring of a ULX, using more than 4 yr of observations from the Swift satellite. We find that the 115 d periodicity reported by Strohmayer disappeared after only a few cycles, confirming the suspicion of Foster et al. that the periodicity is most likely superorbital and not the orbital period of the system. We also report on a clear dipping behaviour of the source that may be related to a (super)orbital phenomenon. All these features are reminiscent of Galactic X-ray binaries and strengthen their link with ULXs. Deeper observations of a dip could help resolve the ambiguity about the interpretation of the spectral components of ULXs.
作者：
F. Grise et al.
期刊：
MNRAS 433, 1023 (2013)
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