A 78 Day X-Ray Period Detected from NGC 5907 ULX1 by Swift

Journal
THE ASTROPHYSICAL JOURNAL
Date Issued
2016
Author(s)
Walton, D. J.
•
Fürst, F.
•
•
Barret, D.
•
Brightman, M.
•
Fabian, A. C.
•
Gehrels, N.
•
Harrison, F. A.
•
Heida, M.
•
Middleton, M. J.
•
Rana, V.
•
Roberts, T. P.
•
Stern, D.
•
Tao, L.
•
Webb, N.
DOI
10.3847/2041-8205/827/1/L13
Abstract
We report the detection of a 78.1 ± 0.5 day period in the X-ray light curve of the extreme ultraluminous X-ray source NGC 5907 ULX1 ({L}{{X,peak}}∼ 5× {10}40 erg s-1), discovered during an extensive monitoring program with Swift. These periodic variations are strong, with the observed flux changing by a factor of ∼3-4 between the peaks and the troughs of the cycle; our simulations suggest that the observed periodicity is detected comfortably in excess of 3σ significance. We discuss possible origins for this X-ray period, but conclude that at the current time we cannot robustly distinguish between orbital and super-orbital variations.
Volume
827
Issue
1
Start page
L13
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