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Quasi-periodic dipping in the ultraluminous X-ray source, NGC 247 ULX-1

Alston, W.N.; Pinto, C.; Barret, D.; D'Ai, A.; Del Santo, M.; Earnshaw, H.; Fabian, A.C.; Fuerst, F.; Kara, E.; Kosec, P.; Middleton, M.J.; Parker, M.L.; Pintore, F.; Robba, A.; Roberts, T.P.; Sathyaprakash, R.; Walton, D.; Ambrosi, E.

Quasi-periodic dipping in the ultraluminous X-ray source, NGC 247 ULX-1 Thumbnail


Authors

W.N. Alston

C. Pinto

D. Barret

A. D'Ai

M. Del Santo

H. Earnshaw

A.C. Fabian

F. Fuerst

E. Kara

P. Kosec

M.J. Middleton

M.L. Parker

F. Pintore

A. Robba

R. Sathyaprakash

D. Walton

E. Ambrosi



Abstract

Most ultraluminous X-ray sources (ULXs) are believed to be stellar mass black holes or neutron stars accreting beyond the Eddington limit. Determining the nature of the compact object and the accretion mode from broad-band spectroscopy is currently a challenge, but the observed timing properties provide insight into the compact object and details of the geometry and accretion processes. Here, we report a timing analysis for an 800 ks XMM–Newton campaign on the supersoft ultraluminous X-ray source, NGC 247 ULX-1. Deep and frequent dips occur in the X-ray light curve, with the amplitude increasing with increasing energy band. Power spectra and coherence analysis reveals the dipping preferentially occurs on ∼5 and ∼10 ks time-scales. The dips can be caused by either the occultation of the central X-ray source by an optically thick structure, such as warping of the accretion disc, or from obscuration by a wind launched from the accretion disc, or both. This behaviour supports the idea that supersoft ULXs are viewed close to edge-on to the accretion disc.

Citation

Alston, W., Pinto, C., Barret, D., D'Ai, A., Del Santo, M., Earnshaw, H., …Ambrosi, E. (2021). Quasi-periodic dipping in the ultraluminous X-ray source, NGC 247 ULX-1. Monthly Notices of the Royal Astronomical Society, 505(3), 3722-3729. https://doi.org/10.1093/mnras/stab1473

Journal Article Type Article
Acceptance Date May 18, 2021
Online Publication Date May 25, 2021
Publication Date 2021-08
Deposit Date May 26, 2021
Publicly Available Date Nov 16, 2021
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 505
Issue 3
Pages 3722-3729
DOI https://doi.org/10.1093/mnras/stab1473
Related Public URLs https://arxiv.org/pdf/2104.11163.pdf

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Copyright Statement
This article has been accepted for publication in Monthly notices of the Royal Astronomical Society. ©: 2021 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.







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