Abstract
ACTIVE galactic nuclei (AGNs) exhibit high luminosity with rapid variability, especially in X-ray emission, for which the luminosity can be greater than that of a normal galaxy, and the variability timescale implies an emitting region in some cases smaller than one light hour1. The hard X-ray spectrum of AGNs is nonthermal, probably arising from an electron–positron pair cascade, with some emission reflected off relatively cold matter2,3. Energy can be pumped into a cascade by any process that produces relativistic pairs, but because electrons and positrons are hard to accelerate efficiently, there has been interest in models in which protons are accelerated4,5, and create relativistic electrons on interaction with a local radiation field6–8. Here we show that a sufficient column density of protons can lead to runaway pair production: photons generated by the relativistic pairs are the targets for the protons to produce more pairs. This process can produce X-ray flares with the observed characteristics, and our model predicts the maximum ratio of luminosity to source size ('compactness') as well as their spectrum in the early phases. The same mechanism may also be able to create the knots of synchrotron-radiating pair plasma seen in sources such as 3C273.
This is a preview of subscription content, access via your institution
Access options
Subscribe to this journal
Receive 51 print issues and online access
$199.00 per year
only $3.90 per issue
Buy this article
- Purchase on Springer Link
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
References
Done, C. & Fabian, A. C. Mon. Not. R. astr. Soc. 240, 81–102 (1989).
Pounds, K. A., Nandra, K., Stewart, G. C., George, I. M. & Fabian, A. C. Nature 344, 132–133 (1989).
Zdziarski, A. A., Ghisellini, G., Svensson, R., Fabian, A. C. & Done, C. Astrophys. J. 363, L1–L4 (1990).
Protheroe, R. J. & Kazanas, D. Astrophys. J. 265, 620–624 (1983).
Kazanas, D. & Ellison, D. C. Astrophys. J. 304, 178–187 (1986).
Sikora, M., Kirk, J. G., Begelman, M. C. & Schneider, P. Astrophys. J. 320, L81–L85 (1987).
Begelman, M. C., Rudak, B. & Sikora, M. Astrophys. J. 362, 38–51 (1990).
Szabo, A. P. & Protheroe, R. J. in Particle Acceleration in Cosmic Plasma (eds Gaisser, T. & Zank, G. P.) (American Institute of Physics, in the press).
Bisnovaty-Kogan, G. S., Zel'dovich, Ya. B. & Sunyaev, R. A. Sov. Astr. 15, 17–22 (1971).
Stern, B. & Svensson, R. in Relativistic Hadrons in Cosmic Compact Objects (eds Zdziarski, A. A. & Sikora, M.) (Springer, Berlin, 1991).
Stern, B. E., Sikora, M. & Svensson, R. in Testing the AGN paradigm (eds Holt, S. S., Neff, S. G. & Megan Urry, C.) 313–316 (American Institute of Physics, New York, 1992).
Guilbert, P. W., Fabian, A. W. & Rees, M. Mon. Not. R. astr. Soc. 205, 593–603 (1983).
Walter, R. & Courvoisier, T. J.-L. Astr. Astrophys. 258, 255–264.
Camenzind, M. in Variability of Active Galaxies (eds Duschl, W. J., Wagner, S. J. & Camenzind, M.) 201–210 (Springer, Berlin, 1991).
Turner, M. J. L. et al. Mon. Not. R. astr. Soc. 244, 310–321 (1990).
Perola, G. C. et al. Astrophys. J. 306, 508–521 (1986).
Yaqoob, T. & Warwick, R. S. Mon. Not. R. astr. Soc. 248, 773–786 (1991).
Lawrence, A., Watson, M. G., Pounds, K. A. & Elvis, M. Nature 325, 694–696 (1987).
Walter, R. & Courvoisier, T. J.-L. Astr. Astrophys. 233, 40–52 (1990).
Zenzus, J. A., Unwin, S. C., Cohen, M. H. & Biretta, J. A. Astr. J. 100, 1777–1784 (1990).
Krichbaum, T. P. et al. Astr. Astrophys. 237, 3–11 (1990).
Bååth, L. B. et al. Astr. Astrophys. 241, L1–L4 (1991).
Svensson, R. Mon. Not. R. astr. Soc. 227, 403–451 (1987).
Sikora, M. & Begelman, M. C. in High Energy Neutrino Astrophysics (ed. Stenger, V. J.) (World Scientific, in the press).
Schlickeiser, R. Astr. Astrophys. 136, 227–236 (1984).
Kirk, J. G. & Mastichiadis, A. Astr. Astrophys. 213, 75–79 (1989).
Mannheim, K. & Biermann, P. L. Astr. Astrophys. 221, 211–220 (1989).
Stecker, F. W., Done, C., Salamon, M. H. & Sommers, P. Phys. Rev. Lett. 66, 2697–2700 (1991).
Mastichiadis, A. & Kirk, J. G. in High Energy Neutrino Astrophysics (ed. Stenger, V. J.) (World Scientific, in the press).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Kirk, J., Mastichiadis, A. X-ray flares from runaway pair production in active galactic nuclei. Nature 360, 135–137 (1992). https://doi.org/10.1038/360135a0
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1038/360135a0
This article is cited by
-
Relaxation of a Two Electron-Temperature Relativistic Hot Electron-Positron-Ion Plasma
Brazilian Journal of Physics (2024)
-
Dynamic behavior of positron acoustic multiple-solitons in an electron–positron-ion plasma
Optical and Quantum Electronics (2024)
-
Ignition of X-ray flares
Nature (1992)
Comments
By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.