Matthew J. Middleton, James C. A. Miller-Jones, Sera Markoff, Rob Fender, Martin Henze, Natasha Hurley-Walker, Anna M. M. Scaife, Timothy P. Roberts, Dominic Walton, John Carpenter, Jean-Pierre Macquart, Geoffrey C. Bower, Mark Gurwell, Wolfgang Pietsch, Frank Haberl, Jonathan Harris, Michael Daniel, Junayd Miah, Chris Done, John Morgan, Hugh Dickinson, Phil Charles, Vadim Burwitz, Massimo Della Valle, Michael Freyberg, Jochen Greiner, Margarita Hernanz, Dieter H. Hartmann, Despina Hatzidimitriou, Arno Riffeser, Gloria Sala, Stella Seitz, Pablo Reig, Arne Rau, Marina Orio, David Titterington, Keith Grainge
A subset of ultraluminous X-ray sources (those with luminosities < 10^40 erg/s) are thought to be powered by the accretion of gas onto black holes with masses of ~5-20 M_solar, probably via an accretion disc. The X-ray and radio emission are coupled in such Galactic sources, with the radio emission originating in a relativistic jet thought to be launched from the innermost regions near the black hole, with the most powerful emission occurring when the rate of infalling matter approaches a theoretical maximum (the Eddington limit). Only four such maximal sources are known in the Milky Way, and the absorption of soft X-rays in the interstellar medium precludes determining the causal sequence of events that leads to the ejection of the jet. Here we report radio and X-ray observations of a bright new X-ray source whose peak luminosity can exceed 10^39 erg/s in the nearby galaxy, M31. The radio luminosity is extremely high and shows variability on a timescale of tens of minutes, arguing that the source is highly compact and powered by accretion close to the Eddington limit onto a stellar mass black hole. Continued radio and X-ray monitoring of such sources should reveal the causal relationship between the accretion flow and the powerful jet emission.
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http://arxiv.org/abs/1212.4698
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