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ULX behaviour: The ultraluminous state, winds and interesting anomalies

Roberts, T. P. and Middleton, M. J. and Sutton, A. D. and Mezcua, M. and Walton, D. J. and Heil, L. M. (2016) ULX behaviour: The ultraluminous state, winds and interesting anomalies. Astronomische Nachrichten, 337 (4-5). pp. 534-540. ISSN 0004-6337. doi:10.1002/asna.201612343.

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Recent evidence - in particular the hard X-ray spectra obtained by {NuSTAR}, and the large amplitude hard X-ray variability observed when ULXs show soft spectra - reveals that common ultraluminous X-ray source (ULX) behaviour is inconsistent with known sub-Eddington accretion modes, as would be expected for an intermediate-mass black hole (IMBH). Instead, it appears that the majority of ULXs are powered by super-Eddington accretion onto stellar-mass black holes. Here, we will review work that delves deeper into ULX spectral-timing behaviour, demonstrating it remains consistent with the expectations of super-Eddington accretion. One critical missing piece from this picture is the direct detection of the massive, radiatively-driven winds expected from ULXs as atomic emission/absorption line features in ULX spectra; we will show it is very likely these have already been detected as residuals in the soft X-ray spectra of ULXs. Finally, we will discuss ULXs that do not appear to conform to the emerging ULX behaviour patterns. In particular we discuss the implications of the identification of a good IMBH candidate as a background QSO; and the confirmation of an IMBH/ULX candidate in the galaxy NGC 2276 via the radio/X-ray fundamental plane.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Roberts, T. P.0000-0001-8252-6337
Middleton, M. J.0000-0002-8183-2970
Walton, D. J.0000-0001-5819-3552
Additional Information:© 2016: WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. TPR acknowledges support from STFC as part of the consolidated grant ST/L00075X/1. MM acknowledges financial support from NASA Chandra Grant G05-16099X. All data used is, or will be, public in the relevant mission archives.
Funding AgencyGrant Number
Science and Technology Facilities Council (STFC)ST/L00075X/1
Subject Keywords:X-rays: binaries – accretion, accretion disks – black hole physics
Issue or Number:4-5
Record Number:CaltechAUTHORS:20160527-093054394
Persistent URL:
Official Citation:Roberts, T. P., Middleton, M. J., Sutton, A. D., Mezcua, M., Walton, D. J. and Heil, L. M. (2016), ULX behaviour: The ultraluminous state, winds and interesting anomalies. Astron. Nachr., 337: 534–540. doi: 10.1002/asna.201612343
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:67434
Deposited By: Joy Painter
Deposited On:27 May 2016 17:27
Last Modified:04 Oct 2022 17:22

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