Resolving the radio core of quiescent black hole X-ray binaries


Radio emission from sub-Eddington black hole X-ray binaries is usually associated with synchrotron emission from steady collimated jets. This association relies on VLBA observations of two very bright sources, GRS 1915+105 and Cyg X-1, emitting X-rays at or above a few per cent of the Eddington limit. It is unclear how the jet properties, notably its size and collimation degree, might change at lower luminosities, in the so called `quiescent' regime. We propose to observe two representative systems with the High Sensitivity Array as part of a wider program aiming to constrain the nature and geometry of the radio emission from sub-Eddington X-ray binaries; A0620--00, the dimmest and closest of all, and V404 Cyg, with the largest orbital period among the quiescent systems. Together with Cyg X-1 and GRS 1915+105, high spatial resolution observations of A0620--00 and V404 Cyg would span more than 9 orders of magnitude in luminosity, allowing us to test theoretical predictions on how the jet angular size may scale with the system parameters.

Name Other * Institution Email Phone
Elena Gallo PI UC Santa Barbara
Peter Jonker CfA
James Miller-Jones Oxford
Robert Fender U Southampton
Tom Maccarone U Southampton 442380597584
* PI = Principal Investigator; CO = Contact author; T = Thesis observations; S = Student

Front Ends
Gregorian X(8.2 to 10.0 GHz)

Back Ends
VLBA recorder and DAR

Type of Observing
Monitor Very Long Baseline Interferometry

Switching Type

Processor (correlator)

Allotted time 1.50 hours

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Updated 09/19/2007