2006MNRAS.369..603F -
Mon. Not. R. Astron. Soc., 369, 603-607 (2006/June-3)
A transient relativistic radio jet from Cygnus X-1.
FENDER R.P., STIRLING A.M., SPENCER R.E., BROWN I., POOLEY G.G., MUXLOW T.W.B. and MILLER-JONES J.C.A.
Abstract (from CDS):
We report the first observation of a transient relativistic jet from the canonical black hole candidate, Cygnus X-1, obtained with the Multi-Element Radio-Linked Interferometer Network (MERLIN). The jet was observed in only one of six epochs of MERLIN imaging of the source during a phase of repeated X-ray spectral transitions in 2004 Jan-Feb, and this epoch corresponded to the softest 1.5-12keV X-ray spectrum. With only a single epoch revealing the jet, we cannot formally constrain its velocity. Nevertheless, several lines of reasoning suggest that the jet was probably launched 0.5-4.0d before this brightening, corresponding to projected velocities of 0.2c ≲ vapp≲ 1.6c, and an intrinsic velocity of ≳0.3c. We also report the occurrence of a major radio flare from Cyg X-1, reaching a flux density of ∼120mJy at 15GHz, and yet not associated with any resolvable radio emission, despite a concerted effort with MERLIN. We discuss the resolved jet in terms of the recently proposed `unified model' for the disc-jet coupling in black hole X-ray binaries, and tentatively identify the `jet line' for Cyg X-1. The source is consistent with the model in the sense that a steady jet appears to persist initially when the X-ray spectrum starts softening, and that once the spectral softening is complete the core radio emission is suppressed and transient ejecta/shock observed. However, there are some anomalies, and Cyg X-1 clearly does not behave like a normal black hole transient in progressing to the canonical soft/thermal state once the ejection event has happened.
Abstract Copyright:
2006 The Authors. Journal compilation © 2006 RAS
Journal keyword(s):
accretion, accretion discs - black hole physics - ISM: jets and outflows - X-rays: binaries
Simbad objects:
9
Full paper
View the references in ADS
To bookmark this query, right click on this link: simbad:2006MNRAS.369..603F and select 'bookmark this link' or equivalent in the popup menu