| The Average X-Ray/gamma-Ray Spectra Of Seyfert Galaxies From Ginga And Osse And The Origin Of The Cosmic X-Ray Background (2008) | |||||||||||||
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| We have obtained the first average 2--500 keV spectra of Seyfert galaxies, using the data from Ginga and GRO OSSE. Our sample contains 3 classes of objects with markedly different spectra: radio-quiet Seyfert 1s and 2s, and radio-loud Seyfert 1s. The average radio-quiet Seyfert 1 spectrum is well-fitted by a power law continuum with the energy spectral index ff ß 0:9, a Compton reflection component corresponding to a ¸ 2ß covering solid angle, and ionized absorption. There is a high-energy cutoff in the incident power law continuum: the e-folding energy is E c ß 0:6 +0:8 \Gamma0:3 MeV. The simplest model that describes this spectrum is Comptonization in a relativistic optically-thin thermal corona above the surface of an accretion disk. Radio-quiet Seyfert 2s show strong neutral absorption, and there is an indication that their X--ray power laws are intrinsically harder, although the Seyfert 1 spectrum with ff = 0:9 and strong reflection cannot be ruled out by the data. Finally, the ... | |||||||||||||
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