Search

By means of quasi-simultaneous radio/X-ray observations of ten Galactic black hole binaries in the low/hard X-ray state, we have found evidence for a strong correlation between these two bands over more than three orders of magnitude in X-ray luminosity, from the ‘quiescent’ regime up to close to the soft state transition, where radio emission starts to decline, probably corresponding to the physical disappearance of the jet. We discuss three main consequences of this work: 1) Monte Carlo simulations show that the observed scatter to the relation is consistent with relatively low beaming (Γradio

Since 1997 we have monitored Cyg X-1 on a bi-weekly timescale with simultaneous X-ray and radio observations with RXTE and the Ryle telescope. We present results from this continuing campaign such as correlations between different timing parameters (X-ray time lag, X-ray coherence function, the rms-flux relation, etc.) and we show that the power spectrum of Cyg X-1 can be well described by the sum of four broad Lorentzian components. The behavior of these components follows the same correlations that were also seen in the Lorentzian decomposition of the power spectra of neutron stars.