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Durham University

Department of Physics

Staff profile

Publication details for Prof Chris Done

Jin, C., Done, C. & Ward, M. J. (2016). Strong constraints on a super-Eddington accretion flow: XMM–Newton observations of an intermediate-mass black hole. Monthly Notices of the Royal Astronomical Society 455(1): 691-702.

Author(s) from Durham


RX J1140.1+0307 is a Narrow Line Seyfert 1 (NLS1) with one of the lowest black hole masses known in an AGN (M ≤ 106 M⊙). We show results from two new XMM–Newton observations, exhibiting soft 2–10 keV spectra, a strong excess at lower energies, and fast X-ray variability which is typical of this class of AGN. The soft excess can be equally well fit using either low-temperature Comptonization or highly smeared, ionized reflection models, but we additionally consider the fast X-ray variability to produce covariance, lag and coherence spectra to show that the low-temperature Comptonization model gives a better description of the break in variability properties between soft and hard X-rays. Both these models require an additional component at the softest energies, as expected from the accretion disc. However, standard disc models cannot connect this to the optical/UV emission from the outer disc unless the mass is underestimated by an order of magnitude. The variable optical and far UV emission instead suggests that L/LEdd ∼ 10 through the outer disc, in which case advection and/or wind losses are required to explain the observed broad-band spectral energy distribution. This implies that the accretion geometry close to the black hole is unlikely to be a flat disc as assumed in the recent X-ray reverberation mapping techniques.