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Interstellar scintillation as the origin of the rapid radio variability of the quasar J1819+3845

Nature volume 415, pages 57–60 (2002)Cite this article

Abstract

The liberation of gravitational energy as matter falls onto a supermassive black hole at the centre of a galaxy is believed to explain the high luminosity of quasars. The variability of this emission from quasars and other types of active galactic nuclei can provide information on the size of the emitting regions and the physical process of fuelling the black hole. Some active galactic nuclei are variable at optical (and shorter) wavelengths, and display radio outbursts over years and decades. These active galactic nuclei often also show faster intraday variability at radio wavelengths3,4. The origin of this rapid variability has been extensively debated5, but a correlation between optical and radio variations in some sources6,7 suggests that both are intrinsic. This would, however, require radiation brightness temperatures that seem physically implausible, leading to the suggestion that the rapid variations are caused by scattering of the emission by the interstellar medium inside our Galaxy8,9. Here we show that the rapid variations in the extreme case of quasar J1819+3845 (ref. 10) indeed arise from interstellar scintillation. The transverse velocity of the scattering material reveals the presence of plasma with a surprisingly high velocity close to the Solar System.

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Figure 1: Diagram showing the projection of the interstellar scintillation onto the Solar System.
Figure 2: Results of VLA and WSRT observations on 7 and 12 January 2001.
Figure 3: The calculated delays as a function of observing time for both days of observation.

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Acknowledgements

We thank F. Briggs for the code used to predict the delays. This work was funded by the EU TMR network ‘CERES’. The NRAO is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities. The WSRT operated by ASTRON is supported by the Netherlands Organization for Scientific Research (NWO).

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Authors and Affiliations

  1. Kapteyn Astronomical Institute, University of Groningen, Groningen, 9700 AV, The Netherlands

    J. Dennett-Thorpe & A. G. de Bruyn

  2. Astronomical Institute Anton Pannekoek, University of Amsterdam, Amsterdam, 1098 SJ, The Netherlands

    J. Dennett-Thorpe

  3. ASTRON, PO Box 2, Dwingeloo, 7990 AA, The Netherlands

    A. G. de Bruyn

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Correspondence to A. G. de Bruyn.

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Dennett-Thorpe, J., de Bruyn, A. Interstellar scintillation as the origin of the rapid radio variability of the quasar J1819+3845. Nature 415, 57–60 (2002). https://doi.org/10.1038/415057a

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