2003/05/13 by S. Migliari, Simone Migliari, Rob Fender +11 · 1 citation
Engineering · Physics and Astronomy · #Astrophysical Phenomena and Observations #Mechanics and Biomechanics Studies #Pulsars and Gravitational Waves Research #astro-ph
paper · pdf · doi:10.1046/j.1365-8711.2003.06795.x
published as Mon.Not.Roy.Astron.Soc. 342 (2003) L67 · accepted for publication in MNRAS Letters
arxiv created 2003/05/13 · openalex publication_date 2003/07/04 · arxiv updated 2009/12/01 · openalex created_date 2020/11/23 · openalex updated_date 2026/07/28
We have analysed 12 simultaneous radio (Very Large Array) and X-ray (RXTE) observations of the atoll-type X-ray binary 4U 1728–34, performed in two blocks in 2000 and 2001. We have found that the strongest and most variable emission seems to be associated with repeated transitions between hard (island) and softer (lower banana) X-ray states, while weaker, persistent radio emission is observed when the source is steadily in the hard X-ray state. There is a significant positive ranking correlation between the radio flux density at 8.46 GHz and the 2–10 keV X-ray flux. Moreover, significant positive ranking correlations between radio flux density and X-ray timing features (i.e. break and low-frequency Lorentzian frequencies) have been found. These correlations represent the first evidence for a coupling between disc and jet in an atoll-type X-ray binary. Furthermore, drawing an analogy between the hard (island) state and the low/hard state of black hole binaries, we confirm previous findings that accreting neutron stars are a factor of ∼30 less ‘radio loud’ than black holes.