Long term variability of Cygnus X-1. III. Radio–X-ray correlations

Date

2004-09-28

Department

Program

Citation of Original Publication

Gleissner, T., J. Wilms, G. G. Pooley, M. A. Nowak, K. Pottschmidt, S. Markoff, S. Heinz, M. Klein-Wolt, R. P. Fender, and R. Staubert. “Long Term Variability of Cygnus X-1 - III. Radio–X-Ray Correlations.” Astronomy & Astrophysics 425, no. 3 (October 1, 2004): 1061–68. https://doi.org/10.1051/0004-6361:20040280.

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Attribution 4.0 International (CC BY 4.0)

Subjects

Abstract

Long time scale radio–X-ray correlations in black holes during the hard state have been found in many sources and there seems to emerge a universal underlying relationship which quantitatively describes this behavior. Although it would appear only natural to detect short term emission patterns in the X-ray and – with a certain time lag – in the radio, there has been little evidence for this up to now. The most prominent source for radio–X-ray correlations on short time scales (minutes) so far remains GRS 1915+105 where a single mass ejection could be detected successively in X-ray, IR, and radio wavebands. We analyze a database of more than 4 years of simultaneous radio–X-ray data for Cygnus X-1 from the Ryle Telescope and RXTE PCA/HEXTE. We confirm the existence of a radio–X-ray correlation on long time scales, especially at hard energies. We show that apparent correlations on short time scales in the lightcurves of Cygnus X-1 are most likely the coincidental outcome of white noise statistics. Interpreting this result as a breakdown of radio–X-ray correlations on shorter time scales, this sets a limit to the speed of the jet.