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XMM-Newton campaign on the ultraluminous X-ray source NGC 247 ULX-1: outflows

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

XMM-Newton campaign on the ultraluminous X-ray source NGC 247 ULX-1: outflows Thumbnail


C. Pinto

R. Soria

D. Walton

A. D'Ai

F. Pintore

P. Kosec

W.N. Alston

F. Fuerst

M.J. Middleton

M. Del Santo

D. Barret

E. Ambrosi

A. Robba

H. Earnshaw

A. Fabian


Most ultraluminous X-ray sources (ULXs) are believed to be powered by super-Eddington accreting neutron stars and, perhaps, black holes. Above the Eddington rate the disc is expected to thicken and to launch powerful winds through radiation pressure. Winds have been recently discovered in several ULXs. However, it is yet unclear whether the thickening of the disc or the wind variability causes the switch between the classical soft and supersoft states observed in some ULXs. In order to understand such phenomenology and the overall super-Eddington mechanism, we undertook a large (800 ks) observing campaign with XMM-Newton to study NGC 247 ULX-1, which shifts between a supersoft and classical soft ULX state. The new observations show unambiguous evidence of a wind in the form of emission and absorption lines from highly ionized ionic species, with the latter indicating a mildly relativistic outflow (−0.17c) in line with the detections in other ULXs. Strong dipping activity is observed in the light curve and primarily during the brightest observations, which is typical among soft ULXs, and indicates a close relationship between the accretion rate and the appearance of the dips. The latter is likely due to a thickening of the disc scale height and the wind as shown by a progressively increasing blueshift in the spectral lines.


Pinto, C., Soria, R., Walton, D., D'Ai, A., Pintore, F., Kosec, P., …Fabian, A. (2021). XMM-Newton campaign on the ultraluminous X-ray source NGC 247 ULX-1: outflows. Monthly Notices of the Royal Astronomical Society, 505(4), 5058-5074.

Journal Article Type Article
Acceptance Date Jun 3, 2021
Online Publication Date Jun 10, 2021
Publication Date 2021-08
Deposit Date Jul 2, 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 4
Pages 5058-5074
Related Public URLs


Published Journal Article (3.2 Mb)

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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