An extremely powerful long-lived superluminal ejection from the black hole MAXI J1820+070

J. S. Bright, R. P. Fender, S. E. Motta, D. R.A. Williams, J. Moldon, R. M. Plotkin, J. C.A. Miller-Jones, I. Heywood, E. Tremou, R. Beswick, G. R. Sivakoff, S. Corbel, D. A.H. Buckley, J. Homan, E. Gallo, A. J. Tetarenko, T. D. Russell, D. A. Green, D. Titterington, P. A. WoudtR. P. Armstrong, P. J. Groot, A. Horesh, A. J.van der Horst, E. G. Körding, V. A. McBride, A. Rowlinson, R. A.M.J. Wijers

Research output: Contribution to journalArticlepeer-review


Black holes in binary systems execute patterns of outburst activity where two characteristic X-ray states are associated with different behaviours observed at radio wavelengths. The hard state is associated with radio emission indicative of a continuously replenished, collimated, relativistic jet, whereas the soft state is rarely associated with radio emission, and never continuously, implying the absence of a quasi-steady jet. Here we report radio observations of the black hole transient MAXI J1820+070 during its 2018 outburst. As the black hole transitioned from the hard to soft state, we observed an isolated radio flare, which, using high-angular-resolution radio observations, we connect with the launch of bipolar relativistic ejecta. This flare occurs as the radio emission of the core jet is suppressed by a factor of over 800. We monitor the evolution of the ejecta over 200 days and to a maximum separation of 10″, during which period it remains detectable due to in situ particle acceleration. Using simultaneous radio observations sensitive to different angular scales, we calculate an accurate estimate of energy content of the approaching ejection. This energy estimate is far larger than that derived from the state transition radio flare, suggesting a systematic underestimate of jet energetics.

Original languageEnglish
Pages (from-to)697-703
Number of pages7
JournalNature Astronomy
Issue number7
StatePublished - 1 Jul 2020

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics


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