Simultaneous EUV and X-ray variability of NGC 4051 |
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| Authors: | P Uttley I M MHardy I E Papadakis I Cagnoni A Fruscione |
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| Institution: | Department of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ; Physics Department, University of Crete, PO Box 2208, 710 03 Heraklion, Crete, Greece; SISSA–ISAS, Via Beirut 4, 34014 Trieste, Italy; Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA |
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| Abstract: | We present a flux variability study of simultaneous RXTE and EUVE observations of the highly variable Seyfert galaxy NGC 4051. We find a strong correlation between variability in the EUV and medium-energy X-ray bands, indicating that both are sampling the same power-law continuum. The lag between the two bands is less than 20 ks and, depending on model assumptions, may be <1 ks. We examine the consequences of such a small lag in the context of simple Comptonization models for the production of the power-law continuum. A lag of <1 ks implies that the size of the Comptonizing region is less than 20 Schwarzschild radii for a black hole of mass >106 M⊙. |
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| Keywords: | galaxies: active galaxies: individual: NGC 4051 galaxies: Seyfert X-rays: galaxies |
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