A relativistic jet from Cygnus X-1 in the low/hard X-ray state

A. M. Stirling, R. E. Spencer, C. J. De La Force, M. A. Garrett, R. P. Fender, R. N. Ogley

    Research output: Contribution to journalArticlepeer-review


    We present the detection of a radio-emitting jet from the black hole candidate and X-ray binary source Cygnus X-1. Evidence of a bright core with a slightly extended structure was found on milliarcsecond resolution observations with the Very Long Baseline Array (VLBA) at 15.4 GHz. Later observations with the VLBA [and including the phased-up, Very Large Array (VLA)] at 8.4 GHz show an extended jet-like feature extending to ∼ 15 mas from a core region, with an opening angle of <20. In addition, lower resolution MERLIN observations at 5 GHz show that the source has <10 per cent linear polarization. The source was in the low/hard X-ray state during the observations, and the results confirm the existence of persistent radio emission from an unresolved core and a variable, relativistic (> 0.6c ) jet during this state.
    Original languageEnglish
    Pages (from-to)1273-1278
    Number of pages5
    JournalMonthly Notices of the Royal Astronomical Society
    Issue number4
    Publication statusPublished - 11 Nov 2001


    • Binaries: close
    • ISM: jets and outflows
    • Stars: individual: Cygnus X-1


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