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

Walton, D. J. and Fürst, F. and Bachetti, M. and Barret, D. and Brightman, M. and Fabian, A. C. and Gehrels, N. and Harrison, F. A. and Heida, M. and Middleton, M. J. and Rana, V. and Roberts, T. P. and Stern, D. and Tao, L. and Webb, N. (2016) A 78 Day X-Ray Period Detected from NGC 5907 ULX1 by Swift. Astrophysical Journal Letters, 827 (1). Art. No. L13. ISSN 2041-8205. doi:10.3847/2041-8205/827/1/L13.

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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 x 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.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Walton, D. J.0000-0001-5819-3552
Fürst, F.0000-0003-0388-0560
Bachetti, M.0000-0002-4576-9337
Barret, D.0000-0002-0393-9190
Brightman, M.0000-0002-8147-2602
Fabian, A. C.0000-0002-9378-4072
Harrison, F. A.0000-0003-2992-8024
Heida, M.0000-0002-1082-7496
Middleton, M. J.0000-0002-8183-2970
Rana, V.0000-0003-1703-8796
Roberts, T. P.0000-0001-8252-6337
Stern, D.0000-0003-2686-9241
Additional Information:© 2016 The American Astronomical Society. Received 2016 June 27; revised 2016 July 20; accepted 2016 July 22; published 2016 August 5. The authors would like to thank the reviewer for their timely and positive feedback, which helped to improve the final manuscript. A.C.F. acknowledges support from ERC Advanced Grant 340442. The work of D.J.W./D.S. was performed at JPL/Caltech, under contract with NASA. D.B. and N.W. acknowledge financial support from the French Space Agency (CNES), M.J.M. acknowledges support from an Ernest Rutherford STFC fellowship, and T.P.R. acknowledges support from the STFC consolidated grant ST/L00075X/1. This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester, and also made use of the XRT Data Analysis Software (XRTDAS) developed under the responsibility of the ASI Science Data Center (ASDC), Italy. We acknowledge the use of public data from the Swift data archive. This research has also made use of a collection of ISIS functions (ISISscripts) provided by ECAP/Remeis observatory and MIT. Facility: Swift. -
Group:Space Radiation Laboratory
Funding AgencyGrant Number
European Research Council (ERC)340442
Centre National d'Études Spatiales (CNES)UNSPECIFIED
Science and Technology Facilities Council (STFC)ST/L00075X/1
Subject Keywords:black hole physics – X-rays: binaries – X-rays: individual (NGC 5907 ULX1)
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory2016-50
Issue or Number:1
Record Number:CaltechAUTHORS:20160810-130314275
Persistent URL:
Official Citation:D. J. Walton et al 2016 ApJ 827 L13
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:69543
Deposited By: Tony Diaz
Deposited On:10 Aug 2016 21:42
Last Modified:11 Nov 2021 04:16

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