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Durham University

Department of Physics

Staff profile

Publication details for Prof Tim Roberts

Sutton, A. D., Roberts, T. P., Gladstone, J. C. & Walton, D. J. (2015). The hyperluminous X-ray source candidate in IC 4320: another HLX bites the dust. Monthly Notices of the Royal Astronomical Society 450(1): 787-793.

Author(s) from Durham


The known members of the class of hyperluminous X-ray sources (HLXs) are few in number, yet they are of great interest as they are regarded as the likeliest intermediate-mass black hole (IMBH) candidates amongst the wider population of ultraluminous X-ray sources (ULXs). Here we report optical photometry and spectroscopy of an HLX candidate associated with the galaxy IC 4320, that reveal it is a background AGN. We discuss the implications of the exclusion of this object from the small number of well-studied HLXs, that appears to accentuate the difference in characteristics between the good IMBH candidate ESO 243-49 HLX-1 and the small handful of other HLXs.