VLBI constraints on the “Jet-line” of Cygnus X-1

Anthony Rushton, James Miller-Jones, Zsolt Paragi, Thomas Maccarone, Guy Pooley, Valeriu Tudose, Rob Fender, Ralph Spencer, Vivek Dhawan, Michael Garrett

Research output: Contribution to journalConference articlepeer-review


Results are presented from recent VLBI observations of Cygnus X-1 during X-ray spectral state changes. Using the EVN in e-VLBI mode and the VLBA with disk recording, we observed the X-ray binary at very high angular resolution and studied changes in the compact jets as the source made transitions from hard X-ray states to softer states. The radio light curves show that these transitions were accompanied by radio flaring events followed by a quenching of the radio emission, as expected from the current paradigm for disc-jet coupling in X-ray binaries. While we see structural changes in the compact jets during these transitions, there was no evidence for the expected ejection of bright, relativistically-moving jet knots. However, we find strong evidence that the jet does not switch off completely in the soft X-ray state of Cygnus X-1, such that a weak, compact jet persists during this phase of radio quenching.

Original languageEnglish
JournalProceedings of Science
StatePublished - 2010
Event10th European VLBI Network Symposium and EVN Users Meeting: VLBI and the New Generation of Radio Arrays, EVN Symposium 2010 - Manchester, United Kingdom
Duration: Sep 20 2010Sep 24 2010


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