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

Walton, D.J.; Fürst, F.; Bachetti, M.; 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

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

Walton, D.J.; Fürst, F.; Bachetti, M.; 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.

Authors

D.J. Walton

F. Fürst

M. Bachetti

D. Barret

M. Brightman

A.C. Fabian

N. Gehrels

F.A. Harrison

M. Heida

M.J. Middleton

V. Rana

Professor Tim Roberts t.p.roberts@durham.ac.uk
Professor

D. Stern

L. Tao

N. Webb

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 (${L}_{{\rm{X,peak}}}\sim 5\times {10}^{40}$ 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.

Citation

Walton, D., Fürst, F., Bachetti, M., Barret, D., Brightman, M., Fabian, A., …Webb, N. (2016). A 78 Day X-Ray Period Detected from NGC 5907 ULX1 by Swift. Astrophysical Journal Letters, 827(1), Article L13. https://doi.org/10.3847/2041-8205/827/1/l13

Journal Article Type	Article
Acceptance Date	Jul 22, 2016
Online Publication Date	Aug 5, 2016
Publication Date	Aug 5, 2016
Deposit Date	Aug 19, 2016
Publicly Available Date	Aug 23, 2016
Journal	Astrophysical Journal Letters
Print ISSN	2041-8205
Electronic ISSN	2041-8213
Publisher	American Astronomical Society
Peer Reviewed	Peer Reviewed
Volume	827
Issue	1
Article Number	L13
DOI	https://doi.org/10.3847/2041-8205/827/1/l13
Related Public URLs	http://arxiv.org/abs/1607.07448