A transient relativistic radio jet from Cygnus X-1

Abstract

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 1.5-12 keV 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 0.5-4.0 days before this brightening, corresponding to projected velocities of 0.2c < v_app < 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 ~120 mJy at 15 GHz, 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.

Accepted for publication in MNRAS

References in corpus (1)

• Opening angles, Lorentz factors and confinement of X-ray binary jets

Cited by in corpus (23)

• The jet-powered optical nebula of Cygnus X-1
• Accretion geometry of the black-hole binary Cygnus X-1 from X-ray polarimetry
• Radio Frequency Timing Analysis of the Compact Jet in the Black Hole X-ray Binary Cygnus X-1
• A new lepto-hadronic model applied to the first simultaneous multiwavelength data set for Cygnus X--1
• A classification of the X-ray and radio states of Cyg X-3 and their long-term correlations
• Correlated radio--X-ray variability of Galactic Black Holes: A radio--X-ray flare in Cygnus X-1
• Shell-Shocked: The Interstellar Medium Near Cygnus X-1
• Jet radio emission in Cygnus X-1 and its orbital modulation
• Wind, jet, hybrid corona and hard X-ray flares: multiwavelength evolution of GRO J1655-40 during the 2005 outburst rise
• High hard X-ray polarization in Cygnus X-1 confined to the intermediate hard state: evidence for a variable jet component
• Evidence for periodic accretion-ejection in LSI+61303
• Astroparticles from X-ray Binary Coronae
• Peering into the tilted heart of Cyg X-1 with high-precision optical polarimetry
• Quantifying jet-interstellar medium interactions in Cyg X-1: Insights from dual-frequency bow shock detection with MeerKAT
• The prototype X-ray binary GX 339-4: using TeV gamma-rays to assess LMXBs as Galactic cosmic ray accelerators
• Variability of X-ray polarization of Cyg X-1
• The spectral-timing analysis of Cygnus X-1 with Insight-HXMT
• The inner flow geometry in MAXI J1820+070 during hard and hard-intermediate states
• VHE Gamma-rays from Galactic X-ray Binary Systems
• Multiwavelength modeling the SED of Luminous Supersoft X-ray Sources in Large Magellanic Cloud and Small Magellanic Cloud
• Dimming GRS 1915+105 observed with NICER and Insight--HXMT
• Relativistic hydrodynamical simulations of the effects of the stellar wind and the orbit on high-mass microquasar jets
• Unprecedentedly bright X-ray flaring in Cygnus X-1 observed by INTEGRAL