Hard X-ray states and radio emission in GRS 1915+105 |
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| Authors: | MKlein-Wolt R PFender G GPooley TBelloni SMigliari E HMorgan Mvan der Klis |
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| Institution: | 1Astronomical Institute 'Anton Pannekoek', University of Amsterdam, and Center for High Energy Astrophysics, Kruislaan 403, 1098 SJ, Amsterdam, the Netherlands; 2Mullard Radio Astronomy Observatory, Cavendish Laboratory, Madingley Road, Cambridge CB3 0HE; 3Osservatorio Astronomico di Brera, Via. E. Bianchi 46, I-23870 Merate, Italy; 4Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 0213, USA |
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| Abstract: | We compare simultaneous Ryle Telescope radio and Rossi X-Ray Timing Explorer X-ray observations of the galactic microquasar GRS 1915+105, using the classification of the X-ray behaviour in terms of three states as previously established. We find a strong (one-to-one) relation between radio oscillation events and series of spectrally hard states in the X-ray light curves, if the hard states are longer than ～100 s and are 'well separated' from each other. In all other cases the source shows either low-level or high-level radio emission, but no radio oscillation events. During intervals when the source stays in the hard spectral state for periods of days to months, the radio behaviour is quite different; during some of these intervals a quasi-continuous jet is formed with an almost flat synchrotron spectrum extending to at least the near-infrared. Based on the similarities between the oscillation profiles at different wavelengths, we suggest a scenario which can explain most of the complex X-ray:radio behaviour of GRS 1915+105. We compare this behaviour with that of other black hole sources, and challenge previous reports of a relation between spectrally soft X-ray states and the radio emission. |
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| Keywords: | binaries: close stars: individual: GRS 1915+105 radio continuum: stars X-rays: individual: GRS 1915+105 |
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